• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1451-1457
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• 2013

Recently, new concept of energy systems such as microgrid, smart grid, supergrid, and energy network has been introducing. In this paper, the concept of the centralized micro-energy network, which is an energy community of a building group without district heating system, is introduced. In addition, a mathematical model for optimal operation of the micro-energy network as a main function of an energy management system (EMS) for the micro-energy network is proposed. In order to show the validation, the proposed model is tested through the simulation and analyzed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.69-74
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• 2015

Recently, energy harvesting technology is increasing due to the fossil fuel shortages. Energy harvesting is generating electrical energy from wasted energies as sunlight, wind, waves, pressure, and vibration etc. Energy harvesting is one of the alternatives of fossil fuel. One of the energy harvesting technologies, the piezoelectric energy harvesting has been actively studied. Piezoelectric generating uses a positive piezoelectric effect which produces electrical energy when mechanical vibration is applied to the piezoelectric device. Piezoelectric energy harvesting has an advantage in that it is relatively not affected by weather, area and place. Also, stable and sustainable energy generation is possible. However, the output power is relatively low, so in this paper, newly designed honeycomb shaped piezoelectric energy harvesting device for increasing a generating efficiency. The output characteristics of the piezoelectric harvesting device were analyzed according to the change of parameters by using the finite element method analysis program. One model which has high output voltage was selected and a prototype of the honeycomb shaped piezoelectric harvesting device was fabricated. Experimental results from the fabricated device were compared to the analyzed results. After the AC-DC converting, the power of one honeycomb shaped piezoelectric energy harvesting device was measured 2.3[mW] at road resistance 5.1[$K{\Omega}$]. And output power was increased the number of harvesting device when piezoelectric energy harvesting device were connected in series and parallel.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.470-479
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• 2016

The model based method for energy saving of the separately excited DC motor drive system is proposed in the paper. The accurate power loss model is necessary for this method. Therefore, the adaptive tabu search algorithm is applied to identify the parameters in the power loss model. The field current values for minimum power losses at any load torques and speeds are calculated by the proposed method. The rule based controller is used to control the field current and speed of the motor. The experimental results confirm that the model based method can successfully provide the energy saving for separately excited DC motor drive. The maximum value of the energy saving is 48.61% compared with the conventional drive method.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.111-115
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• 2012

In this paper, a solar energy powered bicycle linked to a wireless sensor network (WSN) which monitors the transfer of solar energy to an electrical energy storage unit and an analysis of its effectiveness is proposed. In order to achieve this goal, a solar-powered bicycle with an attached ZigBee and a far-end wireless network supervisory system is setup. Experimental results prove that our prototype, solar energy powered bicycle, can achieve enough solar energy for charging a two lead-acid battery pack. As a result, the user, through use of a wireless network in the parking period can be kept aware of the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information of the bicycle through an internet interface.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.16-21
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• 2018

As a result of the Fukushima disaster and climate change due to excessive greenhouse gases, international energy affairs are currently focused on establishing safe and environment-friendly policies. To achieve this, Republic of Korea has established a plan for environment-friendly energy supplies. It is expected that policy enforcement will be accompanied by an increase in energy supply costs. An analysis of energy supply costs is necessary before the establishment of any national energy policy. This paper analyzes and compares the energy supply costs accompanying environmental and nuclear energy policies, based on the Korean National Energy Master Plan and the Basic Plan for Long-Term Electricity Supply and Demand, in order to understand the implications of these national energy policies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1009-1018
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• 2018

As the generation of renewable energy increases rapidly, the stability of the grid due to its intermittency becomes a problem. The most appropriate way to solve this problem is to combine and operate the renewable generators with the ESS(Energy Storage System). However, since the revenues of operating the ESS are less than the investment cost, many countries are implementing various incentive policies for encouraging investment of the ESS. In this paper we estimated optimal capacity of the ESS to maximize profits of renewable energy generation businesses under the incentive policy of Korea and analyzed the impact of the incentive policy on the future electric power system of Jeju island. The simulation results show that the incentive policy has significantly improved the profitability of the renewable energy businesses generation business. But the volatility of the net demand has increased as the energy stored in the ESS is discharged intensively at the time of the incentive application.

• Transactions of Materials Processing
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• v.32 no.3
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• pp.153-159
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• 2023

This paper presents the optimal design of a heating system using radiant heating elements for application in smart farms. Smart farming, an advanced agricultural technology, is based on artificial intelligence and the internet of things and promotes crop production. Temperature and humidity regulation is critical in smart farms, and thus, a heating system is essential. Radiant heating elements are devices that generate heat using electrical energy. Among other applications, radiant heating elements are used for environmental control and heating in smart farm greenhouses. The performance of these elements is directly related to their electrical energy consumption. Therefore, achieving a balance between efficient electrical energy consumption and maximum heating performance in smart farms is crucial for the optimal design of radiant heating elements. In this study, the size, electrical energy supply, heat generation efficiency, and heating performance of radiant heating elements used in these heating systems were investigated. The effects of the size and electrical energy supply of radiant heating elements on the heating performance were experimentally analyzed. As the radiant heating element size increased, the heat generation efficiency improved, but the electrical energy consumption also increased. In addition, increasing the electrical energy supply improved both the heat generation efficiency and heating performance of the radiant heating elements. Based on these results, a method for determining the optimal size and electrical energy supply of radiant heating elements was proposed, and it reduced the electrical energy consumption while maintaining an appropriate heating performance in smart farms. These research findings are expected to contribute to energy conservation and performance improvement in smart farming.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.425-429
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• 1990

In order to spread the practical utilization of solar energy, it depends upon how we can increase the efficiency of solar energy conversion system. This paper describes the method for calculating of optimal passive elements values in Maximum Solar Energy Tracking System. And experimental results with those calculated values are presented.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.111-118
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• 2017

The increased diversity of different types of energy sources requires moving towards smart distribution networks. This paper proposes a probabilistic DG (distributed generation) units planning model to determine technology type, capacity and location of DG units while simultaneously allocating ESS (energy storage systems) based on pre-determined capacities. This problem is studied in a wind integrated power system considering loads, prices and wind power generation uncertainties. A suitable method for DG unit planning will reduce costs and improve reliability concerns. Objective function is a cost function that minimizes DG investment and operational cost, purchased energy costs from upstream networks, the defined cost to reliability index, energy losses and the investment and degradation costs of ESS. Electrical load is a time variable and the model simulates a typical radial network successfully. The proposed model was solved using the DICOPT solver under GAMS optimization software.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.165-172
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• 2018

This paper presents a structure of the retail electricity market based on the local pool with LDERP(Local Distributed Energy Resource Provider) for small energy prosumers. LDERP is an operator for the proposed market, which conducts performance measurement and settlement by the distribution plan determined through contract with participants. The trading process is designed similarly to the negawatt market. In the case study, the many-sided conditions of the proposed market are comparatively analyzed with the existing prosumer programs. The results demonstrate the effectiveness of the proposed framework in determining the purpose of market operating for the benefit of participants according to the various situations.