• Journal of information and communication convergence engineering
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• v.21 no.4
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• pp.316-321
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• 2023

In this study, we developed a conversion core that produces power by utilizing the unused magnetic field in a switchboard. The conversion core makes it possible to utilize power that is normally wasted. The conversion core is composed of a core, filter, and battery. A prototype was installed in a switchboard to conduct tests on the output, battery storage, and output boosting of multiple batteries. Energy was harvested from the magnetic field generated by a busbar of the switchboard, and the power conversion ratio of the core yielded 1.08-1.01 mW per 1 A of bus current. Supplying this technology to the market after further R&D and commercialization is expected to greatly assist in the dissemination of energy harvesting, which has not yet spread widely to the general public.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3151-3168
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• 2021

Internet of Things (IoT) connects several objects with embedded sensors and they are capable of exchanging information between devices to create a smart environment. IoT smart devices have limited resources, such as batteries, computing power, and bandwidth, but comprehensive sensing causes severe energy restrictions, lowering data quality. The main objective of the proposal is to build a hybrid protocol which provides high data quality and reduced energy consumption in IoT sensor network. The hybrid protocol gives a flexible and complete solution for sensor selection problem. It selects a subset of active sensor nodes in the network which will increase the data quality and optimize the energy consumption. Since the unused sensor nodes switch off during the sensing phase, the energy consumption is greatly reduced. The hybrid protocol uses Dijkstra's algorithm for determining the shortest path for sensing data and Ant colony inspired variable path selection algorithm for selecting active nodes in the network. The missing data due to inactive sensor nodes is reconstructed using enhanced belief propagation algorithm. The proposed hybrid method is evaluated using real sensor data and the demonstrated results show significant improvement in energy consumption, data utility and data reconstruction rate compared to other existing methods.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.170-177
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• 1998

The purpose of superconducting magnetic bearing flywheel energy storage system(SMB-FESS) is to store unused nighttime electricity as kinetic energy and convert it to electricity during daytime. The SMB-FESS is proposed as an efficient energy storage system because there is no mechanical problems, such as friction and wear The flywheel over SMB is rotated at a high speed, 50,000rpm. The major source of energy loss in the SMB-FESS is vibration of flywheel. Therefore, the vibration characteristics of SMB-FESS should be identified. In this study, the axial/radial stiffness and damping coefficient of SMB are measured by a vibration test. Natural frequencies and natural modes of flywheel and magnet are analyzed by a finite element method. The modal analysis of system is performed using the modal parameters of each component and the measured stiffness/damping coefficient. So, natural at frequencies and mode shapes of the joined system can be obtained. According to critical speed analysis, the system has two rigid conical modes in the low speed range. Nevertheless, the system has not been affected by the critical speed in the main operating range.

• Journal of Forest and Environmental Science
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• v.25 no.2
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• pp.131-138
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• 2009

Recently, various efforts for the extended utilization of woody biomass has been attempted due to the fact that global warming, energy and environmental problems are urgent ones to be solved. Development of new energy sources at our national security level is desperately needed as we depend on almost all of energies supplied from other countries, let alone the economic crisis caused by oil price hike. Woody biomass can be converted to energy by means of thermochemical, biological, or direct combustion processes. Many processes are available for producing bioenergy, such as bioethanol, wood pellet, wood chip, combined heat, and power system. Political support and R&D investment should be provided that can boost the utilization of the wood biomass, the eco-environment, and recyclable and alternative energy resources for national power security. In addition, a long-term strategy that can utilize unused and low efficient woody biomass resources, and systematically collect and manage them in a national level should be set up. Even though the possibility in total exchange of fossil oil with woody biomass is quite low, technology developments of woody biomass for the solution to global warming and environmental problem through its commercialization are expected to grow steadily.

• Journal of the Korea Society of Computer and Information
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• v.16 no.6
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• pp.11-20
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• 2011

In this paper, we propose an optimal scheduling scheme that minimizes the energy consumption of a real-time video task on the multi-core platform supporting dynamic voltage and frequency scaling. Exploiting parallel execution on multiple cores for less energy consumption, the propose scheme allocates an appropriate number of cores to the task execution, turns off the power of unused cores, and assigns the lowest clock frequency meeting the deadline. Our experiments show that the proposed scheme saves a significant amount of energy, up to 67% and 89% of energy consumed by two previous methods that execute the task on a single core and on all cores respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.598-606
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• 2022

With the advancement of industry, the use of various sustainable energy sources and solutions to problems affecting the environment are being actively requested. From this point of view, it is intended to directly burn unused biogas to use it as energy and to solve environmental problems such as greenhouse gases. In this study, a new type of cavity matrix combustor capable of low-emission complete combustion without complex facilities such as separation or purification of biogas produced in small and medium-sized facilities was proposed, and CFD numerical calculation was performed to understand the performance characteristics of this combustor. The cavity matrix combustor consists of a burner with a rectangular porous microwave receptor at the center inside a 3D cavity that maintains a rectangular parallelepiped shape composed of a porous plate that can store heat in the combustor chamber. As a result of numerical calculation, the biogas supplied to the inlet of the combustor is converted to CO and H₂, which are intermediate products, on the surface of the 3D matrix porous burner. And then the optimal combustion process was achieved through complete combustion into CO₂ and H₂O due to increased combustibility by receiving heat energy from the microwave heating receptor.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.732-737
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• 2001

The mathematical method was developed and numerical analyses were carried out with various parameters to provide substantial data for optimal design and operation of urban utility systems. The composition of systems and their specifications, such as co-generation system, heat pump system, incineration system and other heating and cooling system could be obtained through these analyses for various resource and energy requirements in urban area. As results the system constituents and operating characteristics, and their economic performances such as the value of objective function, initial and an operating costs were discussed for various load patterns. The effective system design method and the excepted effects of the several unused energy recovery systems were also briefly discussed with the variation of the buildings and facilities species and their capacities.

• Journal of KSNVE
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• v.9 no.5
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• pp.891-898
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• 1999

The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.48-54
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• 2004

In this study, waste heat of Jeju City Waste Environment Center is investigated and the utilization method is suggested with economical analysis of additional investment that needed for new facility. Energy balance of the typical facilities is considered in this study such as incineration plant and LFG power plant. The payback period of the investment which is used for the LFG power plant waste heat utilization facility is about 2.4 years and the economic profit of the facility during 10 years operation is up to 926 million won.

• Knowledge Management Research
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• v.24 no.1
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• pp.195-221
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• 2023

As the global energy and climate crisis has complicated interests of each country, the agenda that requires a global response has recently been revived. In particular, Korea is highly dependent on energy imports and continues to have high energy consumption, low efficiency of energy consumption, and high greenhouse gas emissions, so innovative and effective energy policies are urgently needed to achieve energy efficiency and carbon neutrality. In this study, among the changes in distributed district energy policy after the integrated energy method was introduced in Korea in the mid-1980's, the case of the "National Heat Map Project" policy implementation is analyzed with a modified multi-flow model. The 10 years of the Lee Myung-bak and Park Geun-hye administrations, the period of study, was a period in which the main paradigm of energy policy shifted to a "distributed energy platform" and policy transitions such as policy agenda setting, policy drift, and policy revision were made. A study on the process would be meaningful.