• Clean Technology
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• v.26 no.2
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• pp.96-101
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• 2020

In this paper, the commercial feasibility of trigeneration, producing heat, power, and hydrogen (CHHP) and using biogas derived from macroalgae (i.e., seaweed biomass feedstock), are investigated. For this purpose, a commercial scale trigeneration process, consisting of three MW solid oxide fuel cells (SOFCs), gas turbine, and organic Rankine cycle, is designed conceptually and simulated using Aspen plus, a commercial process simulator. To produce hydrogen, a solid oxide fuel cell system is re-designed by the removal of after-burner and the addition of a water-gas shift reactor. The cost of each unit operation equipment in the process is estimated through the calculated heat and mass balances from simulation, with the techno-economic analysis following through. The designed CHHP process produces 2.3 MW of net power and 50 kg hr^-1 of hydrogen with an efficiency of 37% using 2 ton hr^-1 of biogas from 3.47 ton hr^-1 (dry basis) of brown algae as feedstock. Based on these results, a realistic scenario is evaluated economically and the breakeven electricity selling price (BESP) is calculated. The calculated BESP is ¢10.45 kWh^-1, which is comparable to or better than the conventional power generation. This means that the CHHP process based on SOFC can be a viable alternative when the technical targets on SOFC are reached.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.296-301
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• 2016

Using high magnetic flux from a 60 Hz high-current cable, a 2 W wireless-powered energy harvesting receiver for sensor operation, internet of things (IoT) devices, and LED lights inside electrical cable tunnels is proposed. The proposed receiver comprises a copper coil with a high number of turns, a ring-shaped ferromagnetic core, a capacitor for compensating for the impedance of the coil in series, and a rectifier with various types of loads, such as sensors, IoT devices, and LEDs. To achieve safe and easy installation around the power cable, the proposed ring-shaped receiver is designed to easily open or close using a clothespin-shaped handle, which is made of highly-insulated plastic. Laminated silicon steel plates are assembled and used as the core because of their mechanical robustness and high saturation flux density characteristic, in which the thickness of each isolated plate is 0.3 mm. The series-connected resonant capacitor, which is appropriate for low-voltage applications, is used together with the proposed receiver coil. The concept of the figure of merit, which is the product weight and cost of both the silicon steel plate and the copper wire, is used for an optimized design; therefore, the weight of the fabricated receiver and the price of raw material is 750 gf and USD $2 each, respectively. The 2.2 W powering capability of the fabricated receiver was experimentally verified with a power cable current of $100A_{rms}$ at 60Hz.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.182-188
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• 2014

For the dissemination of new and renewable energy, Korean government introduced a renewable portfolio standard (RPS) scheme in 2012 after terminating feed-in tariff (FIT) scheme that was introduced in 2004. With the RPS scheme, 64.7% of its own goal (95.7% in PV and 63.3% in non-PV) was achieved in 2012 and 67.2% of that (94.9% in PV, 65% in non-PV) was achieved in 2013. The deployment of PV systems met the goal very well and that of non-PV did not. Recently, Korean government revised the target year of supplying 10% electricity from new and renewable energy from 2022 to 2024 and released a couple of measures on PV area. Recent studies showed that the bankability of a project plays a key role for PV dissemination. Therefore, the dissemination should be assessed from the point of bankability under the RPS scheme and a little adjustment is necessary to achieve the goal. Especially, installing a small size PV (<100 kwp) system needs a minimum REC price or a FIT scheme. In non-PV area, permission process is a common bottleneck and the related regulation should be eased. In addition, to achieve the long term goal, an implementing scenario has to be prepared. Currently, the portion of the waste-gas energy originated from fossil fuel is too large among the new and renewable energy sources and the portion should be lowered or eliminated in the 10% of electricity supply goal. Seoul Metropolitan Government (SMG) has its own FIT scheme for PV dissemination from 2014 SMG and revised the PV tariff from 50 to 100 won/kwh in effective of 2015. It is worth to spread the other provinces.

• KIEAE Journal
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• v.17 no.4
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• pp.67-74
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• 2017

Purpose: As the recent climate environment changes so rapidly, environmental problems such as hot weather and fine dust have occurred, and interest in environmental policies and technology development is increasing in countries around the world. Similarly in the Architecture, researches to reduce greenhouse gas emissions and to reduce energy application are actively conducted. Looking at previous studies, it is analyzed that the electric VRF is more energy efficient than the gas engine VRF. However, energy costs have changed due to recent price hikes and discounts on gas charges due to high electricity consumption in summer. Method: In this study, the actual building of Gas Engine VRF system was modeled using SketchUp program, and EnergyPlus was used to simulate actual building. Also, Electric VRF system was simulated, and compared with Gas Engine VRF system. Result: The total secondary energy requirement of Electric VRF system was 19.6% less than that of the Gas Engine VRF system, But when analyzing with primary energy requirement, EHP used 15.8% more energy. CO2 emissions were also estimated to be 16.9% more EHP. Energy costs were 14.8% more in Electric VRF systems, because their electricity charges are 0.6 to 160% more expensive than gas charges.

• The Journal of Bigdata
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• v.5 no.1
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• pp.227-239
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• 2020

This paper introduces a method for predicting the maximum power demand despite communication errors in industrial sites. Due to the recent policy of de-nuclearization in Korea, the price of electricity is inevitable, and the amount of electricity used and maximum load management for the management of power demand are becoming important issues. Accordingly, it is important to predict and manage peak power. However, problems such as loss and modulation of measured power data occur at industrial sites due to noise generated by various facilities and sensors. It is difficult to predict the exact value when measured effective power data are lost. The study presents a model for predicting and correcting anomalies and missing values when measured effective power data are lost. The models used in this study are expected to be useful in predicting peak power demand in the event of communication errors at industrial sites.

• Journal of Digital Convergence
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• v.15 no.7
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• pp.41-53
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• 2017

This study focuses on the current state of Smart Grid policy in Japan and its problems while the interest in Smart Grid has been increasing since the March 2011 earthquake in East Japan. As a result of the analysis, Japan introduced the fixed price buying system of new and renewable energy in response to the power supply and demand problem caused by the 2011 earthquake in East Japan, and established a decentralized green electricity trading market in which electricity generated from new and renewable energy is traded Smart Grid-related projects were implemented as a solution to solve energy crisis and environmental problems at the same time. As a result, we achieved visible results such as suppressing peak power, reducing CO2 emissions, and securing stable supply and demand of energy using renewable energy sources. On the other hand, the improvement of current Smart Grid policy operation in Japan and the introduction of stabilization system of power system, promotion of international standards of domestic technology related to smart grid, and support for strengthening security of smart grid.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.1-7
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• 2012

Natural gas through pipeline is supplied to consumers after its pressure gets down compulsorily. The waste pressure energy of this process can be restored by use of turbo expander which can produce electricity. So, turbo expander conducts two functions - pressure reduction and power generation. The power amount is the enthalpy difference between the inlet and outlet states. The five main factors which affect economic profit are facility price, produced power amount, pre-heating amount, electricity cost, and fuel gas cost. Power generation depends mainly on flow amount because inlet and outlet states are fixed. A methodology to estimate economy in irregular flow pattern is proposed and using this way, a case study was carried out.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.127-129
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• 2007

Since the competitive market environment was introduced into the electric power industry, the structure of the industry has been changing from vertically integrated system to functionally unbundled and decentralized system composed of multiple (decision-making) market participants. So the market participants such as Gencos or LSE (load serving entity) need to forecast the market clearing price and thus build their offer or bidding strategies. Not just these market players but also a market operator is required to perform market analysis and ensure simulation capability to manage and monitor the competitive electricity market. For fulfilling the demand for market simulation, many global venders like GE, Henwood, Drayton Analytics, CRA, etc. have developed and provided electricity market simulators. Most of these simulators are based on the optimization formulation which has been used mainly for the least cost resource planning in the centralized power system planning and operation. From this standpoint, it seems somehow inevitable to face many challenges on modeling competitive market based on the method of traditional market simulators. In this paper, we propose a kind of new method, which is MAS based market simulation. The agent based model has already been introduced in EMCAS, one of commercial market simulators, but there may be various ways of modeling agent. This paper, in particular, seeks to introduce an model for MAS based market simulator.

• Clean Technology
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• v.24 no.4
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• pp.357-364
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• 2018

Studies on the production of biogas from third generation biomass, such as micro- and macroalgae, have been conducted through experiments of various scales. In this paper, we investigated the feasibility of commercialization of integrated combined heat and power (CHP) production using biogas derived from macroalgae, i.e., seaweed biomass. For this purpose, an integrated CHP plant of industrial scale, consisting of solid oxide fuel cells, gas turbine and organic Rankine cycle, was designed and simulated using a commercial process simulator. The cost of each equipment in the plant was estimated through the calculated heat and mass balances from simulation and then the techno-economic analysis was performed. The designed integrated CHP process produces 68.4 MW of power using $36ton\;h^{-1}$ of biogas from $62.5ton\;h^{-1}$ (dry basis) of brown algae. Based on these results, various scenarios were evaluated economically and the levelized electricity cost (LEC) was calculated. When the lifetime of SOFC is 5 years and its stack price is $$225kW^{-1}$, the LEC was 12.26 ¢ $kWh^{-1}$, which is comparable to the conventional fixed power generation.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.177-185
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• 2022

In this study, the economic feasibility of a local energy facility that uses forest biomass as an energy source was assessed. We analyzed profitability using data from the Forest Energy Self-sufficient Village Project financed by the Korea Forest Service. The energy facility has a cogeneration generator and wood chip boiler. Wood chip, which has lower heat value and is cheaper than wood pellets, is used as fuel. Revenue comes from the sale of electricity, heat, and renewable energy certificates. Additionally, we considered the sale of carbon credits as substitutes for fossil fuels. The expenditure consists of fuel costs and fixed costs, and the initial investment is treated as a sunk cost. Under the condition of a 55% operation rate and wood chip price of 95,000 KRW per ton, the annual net revenue is positive. Crucial factors for managing the facility sustainably are operation rate and fuel cost. A simulation in which two factors were changed showed that the annual net revenue is negative with a 50% operation rate and 100,000 KRW per ton of wood chip price. To improve net revenue, an increase in the operation rate or a decrease in the wood chip price is required. Additionally, selling carbon credits will make the operation of the facility more profitable. Furthermore, the payment required to procure wood chips could contribute to the rural economy. To foster the use of forest biomass for energy, the price for heat supplied from renewable energy sources should be subsidized.