• 전력전자학회논문지
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• 제17권6호
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• pp.523-531
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• 2012

This paper proposes a high efficiency power conversion system for battery-ultracapacitor hybrid energy storages. The proposed system has only one bidirectional dc-dc converter for hybrid power source with batteries and ultracapacitors. The hybrid power source has bidirectional switching circuits for selecting one energy storage device. Bidirectional power flow between the energy storage device and high voltage capacitor can be controlled by one bidirectional converter. An asymmetrical switching method is applied to the bidirectional converter for high power efficiency. Switching power losses are reduced by zero-voltage switching of power switches. System operation and design considerations are presented. The experimental results are provided to verify the performance of the proposed system.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.168-171
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• 1999

For the axial crushing tests of various shape of tubes, it was reported that composite tubes need trigger mechanism to avoid brittle failure. In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tubes. Glass/Epoxy prepregs were wrapped around aluminum tube and co-cured. The failure of hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to maximum 34% in comparison with aluminum tube. Effective energy absorption is possible for inner aluminum tube because wrapped composite tube constrain the deflection of aluminum tube and reduce the folding length. The failure of hybrid composite tube was stable without trigger mechanism because inner aluminum tube could play the role of crack initiator and controller. Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure due to effective energy absorption capability, easy production, and simple application for RTM process.

• 대한임베디드공학회논문지
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• 제13권3호
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• pp.125-131
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• 2018

STT-RAM is attracting as a next generation Non-volatile memory for replacing cache memory with low leakage energy, high integration and memory access performance similar to SRAM. However, there is problem of write operations as the other Non_volatile memory. Hybrid cache memory using SRAM and STT-RAM is attracting attention as a cache memory structure with lowe power consumption. Despite this, reducing the leakage energy consumption by the STT-RAM is still lacking access to the Dynamic energy. In this paper, we proposed as energy management method such as a way-selection approach for hybrid L2 cache fo SRAM and STT-RAM and memory selection method of write/read operation. According to the simulation results, the proposed hybrid cache memory reduced the average energy consumption by 40% on SPEC CPU 2006, compared with SRAM cache memory.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.208-219
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• 2000

In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tube. Glass/Epoxy prepregs were wrapped around an aluminum tube and co-cured. The failure of the hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to the maximum of 33% in comparison with the aluminum tube. Effective energy absorption is possible for an inner aluminum tube because a wrapped composite tube constrains the deflection of an aluminum tube. The failure of a hybrid composite tube was stable without trigger mechanism because the inner aluminum tube could play the role of the crack initiator and controller. Mean crushing load could be calculated by modifying the plastic hinge collapse model for hybrid materials. The predicted results by this analytical model showed good agreement with the experimental results. It can be said that Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure because this hybrid tube shows effective energy absorption, easy production, and simple application capability for RTM process.

• 전기학회논문지P
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• 제58권4호
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• pp.627-631
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• 2009

As renewable and sustainable energy, solar energy and wind energy have advantages in reducing the pollution sources. The paper presents a hybrid system which includes the solar cell and the wind generator. HOMER provides a platform to design and simulate the power system and then to choose the optimization results. This paper simulates with the HOMER and performs a pre-feasibility study of stand-alone hybrid energy systems for applications in a lab.

• 유공압시스템학회논문집
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• 제6권4호
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• pp.1-8
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• 2009

Nowadays with the high fuel prices, the demands for energy saving and green emission of construction machinery have highly been increased without sacrifice of working performance, safety and reliability. The aim of this paper is to propose a new energy saving hybrid excavator system using an electro-hydraulic actuator driven by an electric motor/generator for the regeneration of potential energy. A 5 ton class excavator is analyzed, developed with the boom for the evaluation of the designed system. The hardware implementation is also presented in this paper. A control strategy for the hybrid excavator is proposed to operate the machine with a highest efficiency. The energy saving ability of the proposed excavator is clearly verified through simulation and experimental results in comparison with a conventional hydraulic excavator.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.30-41
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• 2014

PV/Thennal combined system is a solar energy device that uses photovoltaic module as thermal absorption plate, producing thermal energy as well as electricity which can be utilized in buildings. The system removes heat from PV module through air or liquid and its efficiency will vary dependant on the thermal medium. The heat as the forms of hot air or hot water can be utilized for building use, like space heating and hot water. A significant amount of research and development on hybrid PV/thermal(PVT) collectors has been carried out. This study reviews literature on the research of air-based hybrid PVT collectors in terms of their design and energy performance.

• 전기학회논문지
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• 제56권10호
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• pp.1763-1769
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• 2007

To improve the cycle-life and efficiency of an energy storage system for HEV, a dynamic control system consisted of a switch between a battery and an ultracapacitor module is proposed, which is appropriate for mild hybrid vehicle with 42V power net. The switch can be controlled based on the status of the battery and the ultracapacitor module, and a control algorithm that could largely decrease the number of high charging current peak is also implemented. Therefore the cycle life of the battery can be improved such that it is suitable for a mild hybrid vehicle with frequent engine start-stop and regenerative-braking. Also, by maximizing the use of the ultracapacitor, the system efficiency during high current charging and discharging operation is improved. Finally, this system has the effects that improves the efficiency of energy storage system and reduces the fuel consumption of a vehicle. To verify the validity of the proposed system, this paper presented cycles test results of different energy storage systems: a simple VRLA battery, hybrid energy Pack (HEP, a VRLA battery in Parallel with Ultracapacitor) and a HEP with a switch that controlled by energy management system (EMS). From the experimental result, it was proved the effectiveness of the algorithm.

• 세라미스트
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• 제23권1호
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• pp.54-88
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• 2020

Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2138-2145
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• 2017

A hybrid system combining renewable technologies with diesel generators is a promising solution for rural electrification. Myanmar has many renewable energy resources, and many regions that cannot be supplied with electricity from the main grid. Therefore, in this study, we select a village in Myanmar, which is located far away from the substation, and evaluate the economic feasibility of a hybrid system for the village considering the specific local conditions and resource availability. We consider a hybrid system composed of a photovoltaic source, diesel generator, battery energy storage system, and converter. The load profiles of the household data from the village, and the solar radiation profiles are determined. The advantages of the hybrid system, in terms of cost, reliability, and environmental effects are analyzed through simulations using commercial software. The simulation results show that, for the selected village in Myanmar, a hybrid system with battery energy storage can reduce the cost and greenhouse gas emissions while maintaining reliability. We also obtain an optimized design in terms of the component size for the selected hybrid system with battery energy storage.