• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.17-21
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• 2007

In this paper, we propose new on-line processor management algorithms that manage heterogeneous multimedia services while maximizing energy efficiency. These online management mechanisms are combined in an integrated scheme for higher system performance and energy efficiency. The most important feature of our proposed scheme is its adaptability, flexibility and responsiveness to current network conditions. Simulation results clearly indicate the superior performance of our proposed scheme to strike the appropriate performance balance between contradictory requirements.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.247-255
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• 2018

This paper proposes a transformer design of a direct cell-to-cell active cell balancing circuit with a multi-winding transformer for battery management system (BMS) applications. The coupling coefficient of the multi-winding transformer and the output capacitance of MOSFETs significantly affect the balancing current transfer efficiency of the cell balancing operation. During the operation, the multi-winding transformer stores the energy charged in a specific source cell and subsequently transfers this energy to the target cell. However, the leakage inductance of the multi-winding transformer and the output capacitance of the MOSFET induce an abnormal energy transfer to the non-target cells, thereby degrading the transfer efficiency of the balancing current in each cell balancing operation. The impacts of the balancing current transfer efficiency deterioration are analyzed and a transformer design methodology that considers the coupling coefficient is proposed to enhance the transfer efficiency of the balancing current. The efficiency improvements resulting from the selection of an appropriate coupling coefficient are verified by conducting a simulation and experiment with a 1 W prototype cell balancing circuit.

• Journal of Korea Ship Safrty Technology Authority
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• s.33
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• pp.53-62
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• 2012

Pumps are used widely in feed water, cooling & heating system and process line of industrial and construction fields. They consume nearly 20% of the each nation's total electrical energy. But The management of pump energy wasn't controlled well. Their loss of energy is huge if they have been operated at low efficiency. The first buying cost of pump is small compare to the power consumption of pump, so we can recommend the suitable replace time and best operating condition of parts and pump to measure the pump efficiency. Pump efficiency is usually measured according to the two methods which they are called thermodynamic method and traditional technique. And we measured the pump efficiency using two methods using potable pump efficiency measurement device and compared the results with the real performance curve offered from pump maker.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.742-751
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• 2018

Electric vehicles (EV) are emerging as the future transportation vehicle reflecting their potential safe environmental advantages. Vehicle to Grid (V2G) system describes the hybrid system in which the EV can communicate with the utility grid and the energy flows with insignificant effect between the utility grid and the EV. The paper presents an optimal power control and energy management strategy for Plug-In Electric Vehicle (PEV) charging stations using Wind-PV-FC-Battery renewable energy sources. The energy management optimization is structured and solved using Multi-Objective Particle Swarm Optimization (MOPSO) to determine and distribute at each time step the charging power among all accessible vehicles. The Model-Based Predictive (MPC) control strategy is used to plan PEV charging energy to increase the utilization of the wind, the FC and solar energy, decrease power taken from the power grid, and fulfil the charging power requirement of all vehicles. Desired features for EV battery chargers such as the near unity power factor with negligible harmonics for the ac source, well-regulated charging current for the battery, maximum output power, high efficiency, and high reliability are fully confirmed by the proposed solution.

• Journal of Distribution Science
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• v.18 no.9
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• pp.67-75
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• 2020

Purpose: The purpose of this study is to enhance sales promotion efficiency for using solid refuse fuel facilities. Renewable energy technology using Solid Refuse Fuel (SRF) is an economic efficiency technology that recovers waste by burning various wastes. A survey on the pollutants discharged from the solid fuels facilities was investigated so that the SRF facilities could be expanded, distributed and reflected in the policy. Research design, data, and methodology: In this study, 9 business sites using SRF and Bio-SRF as main raw materials were investigated for 2 years. The characteristics of target business sites such as the type of fuel used, combustion method, combustion temperature, daily fuel consumption and environmental prevention facilities were studied. Results: The average pollution & ammonia concentration of Bio-SRF facilities was found to be 88.15% higher than that of SRF facilities. But the average acetaldehyde concentration of SRF facilities was found to be 88.15% higher than that of Bio-SRF facilities. Conclusions: The main issue is how much electric power generation using combustible materials affects air pollution. The waste recycling law provides the standard value according to the fuel property, but there is a considerable gap with the mixed fuel. Therefore, for efficient utilization of facilities using solid fuel products, additional research is needed to improve the distribution structure of exhaust pollutants is needed.

• Smart Structures and Systems
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• v.14 no.4
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.10
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• pp.3834-3857
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• 2021

The design of cluster-based routing protocols is necessary for Wireless Sensor Networks (WSN). But, due to the lack of features, the traditional methods face issues, especially on unbalanced energy consumption of routing protocol. This work focuses on enhancing the security and energy efficiency of the system by proposing Energy Efficient Based Secure Routing Protocol (EESRP) which integrates trust management, optimization algorithm and key management. Initially, the locations of the deployed nodes are calculated along with their trust values. Here, packet transfer is maintained securely by compiling a Digital Signature Algorithm (DSA) and Elliptic Curve Cryptography (ECC) approach. Finally, trust, key, location and energy parameters are incorporated in Particle Swarm Optimization (PSO) and meta-heuristic based Harmony Search (HS) method to find the secure shortest path. Our results show that the energy consumption of the proposed approach is 1.06mJ during the transmission mode, and 8.69 mJ during the receive mode which is lower than the existing approaches. The average throughput and the average PDR for the attacks are also high with 72 and 62.5 respectively. The significance of the research is its ability to improve the performance metrics of existing work by combining the advantages of different approaches. After simulating the model, the results have been validated with conventional methods with respect to the number of live nodes, energy efficiency, network lifetime, packet loss rate, scalability, and energy consumption of routing protocol.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.364-368
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• 2013

Vibrational energy harvester based on piezoelectricity has been expected to be the dominant energy harvesting technology due to the advantages of high conversion efficiency, light weight and small size, night operation, etc. Its commercialization is just around the corner but the integration with power management electronics should be solved in advance. In this paper, therefore, fully-integrated design environment for piezoelectric energy harvesting systems is presented to assist co-design with the power management electronics. The proposed design environment is capable of analyzing the energy harvester including the package-induced damping effects and simulating the device and its power management electronics simultaneously. When the developed design environment was applied to the fabricated device, the simulated resonant frequency matched well with the experimental result with a difference of 2.97% only. Also, the complex transient response was completed in short simulation time of 3,001 seconds including the displacement distribution over the device geometry. Furthermore, a full-bridge power management circuit was modeled and simulated with the energy harvester simultaneously. Therefore the proposed, fully-integrated design environment is accurate and fast enough for the contribution on successful commercialization of piezoelectric energy harvester.

• Smart Media Journal
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• v.7 no.2
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• pp.71-77
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• 2018

This paper proposes the components of the energy management system (EMS) for optimum operation of renewable energy and associated energy storage system (ESS), the functions to be considered in designing, the analysis of operational effects, and finally the reduction of electricity costs. To accomplish the objectives, a lithium-ion battery system and an energy management system have installed in a PV system, and it presents the results analyzed with operation data for a year. To increase the system operation efficiency, we propose the effect that EMS is used to replace the demand power at the peak time with the charge power at the light load time, which suggests the influence of contributing to the charge benefit and load leveling according to the ESS tariff.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.205-215
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• 2024

This study introduced a direct contact heat exchanger to enhance the efficiency of polymer electrolyte membrane fuel cells (PEMFCs) systems. According to previous research, 28% of the operating costs of fuel cell systems are attributed to heat exchanger devices, prompting the design of a direct contact heat exchanger to address this issue. Optimal configurations were determined through computational fluid dynamics analysis and experimental device fabrication, and the enhanced heat exchange performance of the heat exchanger was experimentally confirmed. Through this, the contribution of the direct contact heat exchanger to the heat management and efficiency enhancement of PEMFC systems was established.