• ETRI Journal
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• v.45 no.4
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• pp.650-665
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• 2023

A novel smart metering technique capable of anomaly detection was proposed for real-time home power management system. Smart meter data generated in real-time were obtained from 900 households of single apartments. To detect outliers and missing values in smart meter data, a deep learning model, the autoencoder, consisting of a graph convolutional network and bidirectional long short-term memory network, was applied to the smart metering technique. Power management based on the smart metering technique was executed by multi-objective optimization in the presence of a battery storage system and an electric vehicle. The results of the power management employing the proposed smart metering technique indicate a reduction in electricity cost and amount of power supplied by the grid compared to the results of power management without anomaly detection.

• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.14-26
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• 2024

Global efforts continue with the goal of transition to a "carbon neutral (net zero)" society with zero carbon emissions by 2050. For this purpose, the technology of water electrolysis is being developed, which can store electricity generated from renewable energies in large quantities and over a long period of time as hydrogen. Recently, various research and large-scale projects on 'green hydrogen', which has no carbon emissions, are being conducted. In this paper, a comparison of water electrolysis technologies was carried out and, based on data provided by the International Energy Agency (IEA), large-scale water electrolysis demonstration projects were analyzed by classifying them by technology, power supply, country and end user. It is expected that through the analysis of large-scale water electrolysis demonstration projects, research directions and road maps can be provided for the development/implementation of commercial projects in the future.

• Journal of Wind Energy
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• v.14 no.1
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• pp.5-13
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• 2023

The commercialization has been of great importance to the clean energy research sector for investing the wind farm development, but it would be difficult to reach a social consensus on the need to expand the economic feasibility of renewable energy due to the lack of reliable and continuous information on levelized cost of Energy (LCOE). Regarding this fact, this paper presents the evaluation of LCOE, focusing on Ulsan offshore region targeting to build the first floating offshore wind farm. Energy production is estimated by the meteorology data combined with the Leanwind Project power curve of an exemplar wind turbine. This work aims to analyze the costs of the Capex depending on site-specific variables. The cost of final LCOE was estimated by using Monte-Carlo method, and it became an average range 297,090 KRW/MWh, a minimum of 251,080 KRW/MWh, and a maximum of 341,910 KRW/MWh. In the year 2021, the SMP (system marginal price) and 4.5 REC (renewable energy certificate) can be paid if 1 MWh of electricity is generated by renewable energy. Considering current SMP and REC price, the floating platform industry, which can earn around 502,000 KRW/MWh, can be finally estimated highly competitive in the Korean market.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.3
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• pp.38-49
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• 2010

The technology of anaerobic digestion of organic wastes has been researched for the production of biogas in various purposes. Biogas comes from anaerobic digestion and landfill in which that of main components are methane and carbon dioxide containing small amount of hydrogen sulfide and ammonia. Biogas can either be used directly on the site where it is generated after proper upgrading or distributed to external customer via separate pipelines like natural gas. There are four basic ways biogas can be utilized such as production of heat and steam, electricity production, vehicle fuel and production of chemicals. There is no international technical standard for biogas use but some countries have developed national standards and procedures for biogas use. In this paper, technical standards of biogas depending on purpose have reviewed for the several countries.

• Journal of Climate Change Research
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• v.4 no.1
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• pp.51-61
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• 2013

To address the problems associated with climate change and energy shortage, Korea has been making efforts to turn waste materials into usable energy. Due to the ongoing efforts to convert waste materials into energy, waste incineration is expanding to utilize the heat generated, and the subsequent greenhouse gas emissions from these waste material incineration are expected to increase. In this study, a municipal waste incineration plant that generates heat and electricity through heat recovery was selected as a subject facility. Methods for estimating the greenhouse gas emissions in the municipal waste incineration plant that was selected as a subject plant were sought, and the greenhouse gas emissions and emission factor were estimated. The $CO_2$ concentrations in discharge gas from the subject facility were on average 6.99%, and the result from calculating this into greenhouse gas emissions showed that the total amount of emissions was $254.60ton\;CO_2/day$. The net emissions, excluding the amount of greenhouse gas emitted from biomass incineration, was shown to be $110.59ton\;CO_2/day$. In addition, after estimating the emissions by separating the heat and electricity generated in the incineration facility, greenhouse gas emission factors were calculated using the greenhouse gas emissions produced per each unit of output. The estimated emission factor for heat was found to be $0.047ton\;CO_2/GJ$ and the emission factor for electricity was found to be $0.652ton\;CO_2/MWh$. The estimated emission factor was shown to be about 17% lower than the $0.783ton\;CO_2/MWh$ emission factor for thermal power plants that use fossil fuels. Waste material types and fossil carbon contents were evaluated as being the factors that have major effects on the greenhouse gas emissions and emission factor.

• Journal of Internet Computing and Services
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• v.16 no.5
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• pp.29-38
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• 2015

The Energy Storage System stores electricity for later use. This system can store electricity from legacy electric power systems or renewable energy systems into a battery device when demand is low. When there is high electricity demand, it uses the electricity previously stored and enables efficient energy usage and stable operation of the electric power system. It increases the energy usage efficiency, stabilizes the power supply system, and increases the utilization of renewable energy. The recent increase in the global interest for efficient energy consumption has increased the need for an energy storage system that can satisfy both the consumers' demand for stable power supply and the suppliers' demand for power demand normalization. In general, an energy storage system consists of a Power Conditioning System, a Battery Management System, a battery cell and peripheral devices. The specifications of the subsystems that form the energy storage system are manufacturer dependent. Since the core component interfaces are not standardized, there are difficulties in forming and operating the energy storage system. In this paper, the design of the profile structure for energy storage system and realization of private profiling system for energy storage system is presented. The profiling system accommodates diverse component settings that are manufacturer dependent and information needed for effective operation. The settings and operation information of various PCSs, BMSs, battery cells, and other peripheral device are analyzed to define profile specification and structure. A profile adapter software that can be applied to energy storage system is designed and implemented. The profiles for energy storage system generated by the profile authoring tool consist of a settings profile and operation profile. Setting profile consists of configuration information for energy device what composes energy saving system. To be more specific, setting profile has three parts of category as information for electric control module, sub system, and interface for communication between electric devices. Operation profile includes information in relation to the method in which controls Energy Storage system. The profiles are based on standard XML specification to accommodate future extensions. The profile system has been verified by applying it to an energy storage system and testing charge and discharge operations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.397-402
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• 2016

To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.4
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• pp.88-100
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• 2013

This study evaluated the direct and indirect environmental impacts of various unit operations of a industrial waste incineration plant by using the life cycle assessment tool and reviewed the improvement plan. During the incineration process, the direct environmental impact was decreased with decrease in emission of various air pollutants by incorporating an air pollution prevention facilities. However, an increase in indirect environmental impacts was observed as a consequence of resources and energy of consumption at the various operational facilities. Consequently, quantitative direct and indirect impact were 89.1%, 10.9%, respectively. The environmental impact analysis of system revealed the highest impact of incineration followed by the impacts of other unit processes such as semidry reactor, and bag-filter. The various air pollutants and ashes generated during the incineration process caused the most significant environmental impact. Among the various categories of environmental impact, global warming accounted the highest impact(more than 85%) followed by eutrophication, and abiotic depletion. As a result of the avoided impact by the utilization of heat generated during the waste incineration process, using an incineration heat for steam and electricity obtained the impact reduction of 45.5%, 19.8%. So, during siting of new incineration plant, the utilization of steam generated from the waste combustion is highly considered to reduce the environmental impact.

• Journal of Acupuncture Research
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• v.26 no.6
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• pp.101-110
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• 2009

Objectives : We developed and proposed a guideline for safety and performance assessment of electric cupping apparatus(Class 2 medical device). Methods : We drafted the guideline for safety and performance assessment of electric cupping apparatus by referring the existing standards and guideline, based on online questionnaire for Korean medical doctors and measurement data from commercially available products. Physical dimension of cups and inner vacuum pressure were acquired for the measurement in order to achieve the purposes. Results : This guideline only can be applied to electric cupping apparatus for enhancing blood circulation by employing negative pressure generated by electricity. Seven items of appearance and label, operation test of pump, variation test of input electricity, vacuum level test, vacuum sustain test, cup-size dependent test, noise level test are suggested for evaluation subjects and methods required for electric cupping devices. Requirements for the design and development of electric cupping devices are suggested: vacuum level indicator, vacuum generation rate, pressure control, valve detachment stability, cup comparability, safety measure, surge protection, user friendliness, instruction for use (IFU). Conclusions : We proposed a guideline for safety and performance assessment of electric cupping apparatus to improve the quality of relating products and aid the commercialization of them, by aiming higher industrial competitiveness of the medical device sectors in Korea. Discussion with related institutes such as industry, academy and government is further required. Public hearings also need to be held prior to the establishment of a final guideline and standard.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.161-166
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• 2007

Photovoltaic (PV) technology permits the transformation of solar light directly into electricity. For the last five years, the photovoltaic sector has experienced one of the highest growth rates worldwide (over 30% in 2006) and for the next 20 years, the average production growth rate is estimated to be between 27% and 34% annually. Currently the cost of electricity produced using photovoltaic technology is above that for traditional energy sources, but this is expected to fall with technological progress and more efficient production processes. A large scale production of solar grade silicon material of high purity could supply the world demand at a reasonably lower cost. A shift from crystalline silicon to thin film is expected in the future. The technical limit for the conversion efficiency is about 30%. It is assumed that in 2030 thin films will have a major market share (90%) and the share of crystalline cells will have decreased to 10%. Our research at Sungkyunkwan University of South Korea is confined to crystalline silicon solar cell technology. We aim to develop a technology for low cost production of high efficiency silicon solar cell. We have successfully fabricated silicon solar cells of efficiency more than 16% starting with multicrystalline wafers and that of efficiency more than 17% on single crystalline wafers with screen printing metallization. The process of transformation from the first generation to second generation solar cell should be geared up with the entry of new approaches but still silicon seems to remain as the major material for solar cells for many years to come. Local barriers to the implementation of this technology may also keep continuing up to year 2010 and by that time the cost of the solar cell generated power is expected to be 60 cent per watt. Photovoltaic source could establish itself as a clean and sustainable energy alternate to the ever depleting and polluting non-renewable energy resource.