• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.20-28
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• 2016

This paper presents a generation rescheduling method for the enhancement of transient stability in power systems. The priority and the candidate generators for rescheduling are calculated by using the energy margin sensitivity. The generation rescheduling formulates the Lagrangian function with the fuel cost and emission such as NO_x and SO_x from power plants. The generation rescheduling searches for the solution that minimizes the Lagrangian function by using the Newton’s approach. While the Pareto optimum in the fuel cost and emission minimization has a drawback of finding a number of non-dominated solutions, the proposed approach can explore the non-inferior solutions of the multiobjective optimization problem more efficiently. The method proposed is applied to a 4-machine 6-bus system to demonstrate its effectiveness.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1386-1396
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• 2017

In this paper, a new approach is proposed to select the optimal sitting and sizing of distributed solar photovoltaic generation (SPVG) in a radial electrical distribution systems (EDS) considering load/generation uncertainties. Here, distributed generations (DGs) allocation problem is modeled as optimization problem with network loss based objective function under various equality and inequality constrains in an uncertain environment. A boundary power flow is utilized to address the uncertainties in load/generation forecasts. This approach facilitates the consideration of random uncertainties in forecast having no statistical history. Uncertain solar irradiance is modeled by beta distribution function (BDF). The resulted optimization problem is solved by a new Dynamic Harmony Search Algorithm (DHSA). Dynamic band width (DBW) based DHSA is proposed to enhance the search space and dynamically adjust the exploitation near the optimal solution. Proposed approach is demonstrated for two standard IEEE radial distribution systems under different scenarios.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2043-2050
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• 2017

This paper presents two MPC (Model Predictive Control) based charging and discharging algorithms of BESS (Battery Energy Storage System) for capacity firming of wind generation. To deal with the intermittency of the output of wind generation, a single BESS is employed. The proposed algorithms not only make the output of combined systems of wind generation and BESS track the predefined reference, but also keep the SoC (State of Charge) of BESS within its physical limitation. Since the proposed algorithms are both presented in simple if-then statements which are the optimal solutions of related optimization problems, they are both easy to implement in a real-time system. Finally, simulations of the two strategies are done using a realistic wind farm library and a BESS model. The results on both simulations show that the proposed algorithms effectively achieve capacity firming while fulfilling all physical constraints.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.250-259
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• 2010

The ability for energy harvesting via the piezoelectric effect was studied for a unimorph element such as piezo buzzer. A simple equivalent circuit was proposed to predict the energy generated based on the internal stress. Unimorphs with a metal-cavity were used as a driving device of the generation panel. Both the AC open voltage and DC output voltage as a function of pressure period and number of element were measured. For the unimorph generation circuit, DC output voltage varies with pressure period, reaching a maximum value at $470{\mu}F$. The maximum output voltage a according to load resistance was measured at $1M{\Omega}$. Data analysis of the DC output voltage and time constant indicated that number of piezoelectric element of optimum was 60~80. It was found that piezoelectric unimorph has the possibility to be used as the driving element of the electric generation.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.29-34
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• 2011

This study examined the effect of environmental variables, such as the NaOH concentration and solution temperature, on the rate of hydrogen generation from NaOH solutions through the corrosion of used aluminum cans as a potential candidate material for the safe and economic production of hydrogen. Corrosion of the used aluminum cans was promoted by increasing the NaOH concentration and solution temperature because of the loss of aluminum passivity. The measured rate of hydrogen generation from the NaOH solutions increased with increasing NaOH concentration due to the catalytic activity of NaOH in the hydrolysis process. However, at higher solution temperatures, the rate of hydrogen generation rate was less affected by the NaOH concentration than that at lower temperature.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.235-240
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• 2008

The recent development of efficient thermal prime movers for distributed generation id changing the focus of the production of electricity from large centralized power plants to local generation units scattered over the territory. The scientific communality is addressing the analysis and planning of the distributed energy resources(der) with wide spread approaches, taking into account technical, environmental, economical and social issues. The coupling of cogeneration system to absorption/electric chillers or heat pumps as well as the interactions with renewable sources, allow for setting up multi-generation systems for building cooling heating and power(BCHP) systems of different energy vectors such as electricity, heat(at different enthalpy levels), cooling power, hydrogen, various chemical substances and so forth. Adoption of the composite multi-generation systems may lead to significant benefits in term of higher efficiency, reduced $CO_2$ emissions and enhanced economy. This paper outlines the main aspects of the BCHP system framework, illistrating its characteristics and summarizing the relevant distributed multi-generation structures.

• Korean Journal of Breeding Science
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• v.42 no.2
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• pp.121-128
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• 2010

Finding alternative and renewable energy sources has become an important goal for plant scientists, especially with the demand for energy increasing worldwide and the supply of fossil fuel being depleted. The most important biofuel to date is bioethanol which is produced from sugars (sucrose and starch) found in corn and sugarcane. Second generation bioethanol is targeting studies that would allow the use of the cell wall (lignocellulose) as a source of carbon by non-food plants. Plant scientists, including breeders, agronomists, physiologists and molecular biologists, are working towards the development of new and improved energy crops especially, how to design crops for bioenergy production and increased biomass generation for biofuel purposes. This review focuses on: i) the current status of first generation bioenergy production, ii) the limitations of first and second generation bioenergy, and iii) ongoing research to overcome challenging issues in second generation bioenergy.

• Journal of the Korean Professional Engineers Association
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• v.33 no.3
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• pp.15-19
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• 2000

The importance of the nuclear energy as one of the national energy sources, safety consideration of the nuclear power plants and status of nuclear power generation and nuclear fuel cycle in Korea are discussed.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.354-356
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• 2000

This paper describes the strategy of a daily optimal operational scheduling on cogeneration systems with each other generation mode. The cogeneration systems consists of three generators. auxiiiary devices which are three auxiliary boilers, two waste boilers and three sludge incinerators. One unit that using the back pressure turbin generates the electrical and the thermal energy. The other two units that using the extraction condensing turbine generate the energy. Auxiliary devices operate to supplement the thermal energy to the thermal load with three units. The cogeneration system has a large capacity which is able to supply enough the thermal energy to the thermal load, however the electric power generated is insufficient to satisfy the electrical load. Therefore the insufficient electric energy is supplemented by buying electrical energy from the utility. Simulation was carried out using optimization toolbox. The result reveals that the proposed modeling and strategy can be effectively applied to cogeneration systems with each other generation mode.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.1
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• pp.3-9
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• 1996

Hydrogen generation by electrical discharge through metal/water system is a viable method for on-demand applications. But its success depends on high energy efficiency defined as the ratio of the amount of consumed metal for a complete reaction with water to the electrical energy input. To improve the energy efficiency the electrical discharge has to sustain the hydrogen generation reaction with a minimal energy dissipation. Some experimental results on the discharge voltage-current profiles are reported and discussed.