• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.537-540
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• 2005

A battery is the primary energy source device presently used in hybrid electric vehicle. It can store much energy, but cannot provide enough current without inefficient units. However, an ultracapcitor can provide much current, but cannot store much energy. It will have better fuel economy by combining the two energy sources in parallel. The purpose of this paper is making the simulator of the two HEV systems. The one has only battery, the other have battery and ultarcapacitor in parallel. To compare the fuel economy, dynamic programing was used for optimization and prius was used for HEV model.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.730-734
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• 2007

National projects on renewable energy and new energy are driven more actively than ever in many countries for the exhaustion of fossil fuel energy from the turn of the century. Such activities began to spread out in railway industry with centering around west European countries. Electric energy is generated on the hybrid vehicle itself, which contributes to reduction of the cost for construction of the infrastructure required for the supply of electric power. Hybrid tram is mainly composed of propulsion system to control electric energy, automatic guidance system to control steering and operation, and central vehicle unit to control and monitor major electronic devices. Generation and supply of electric power are made by the combination of engine generator and battery, or fuel cell and super capacitor.

• ETRI Journal
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• v.44 no.6
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• pp.885-902
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• 2022

The mmWave cell-free massive MIMO (CFmMIMO), combining the advantages of wide bandwidth in the mmWave frequency band and the high- and uniform-spectral efficiency of CFmMIMO, has recently emerged as one of the enabling technologies for 6G. In this paper, we propose a novel framework for energy-efficient mmWave CFmMIMO systems that uses low-resolution digital-analog converters (DACs) and phase shifters (PSs) to introduce lowcomplexity hybrid precoding. Additionally, we propose a heuristic pilot allocation scheme that makes the best effort to slash some interference from copilot users. The simulation results show that the proposed hybrid precoding and pilot allocation scheme outperforms the existing schemes. Furthermore, we reveal the relationship between the energy and spectral efficiencies for the proposed mmWave CFmMIMO system by modeling the whole network power consumption and observe that the introduction of low-resolution DACs and PSs is effective in increasing the energy efficiency by compromising the spectral efficiency and the network power consumption.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.2
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• pp.83-93
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• 2022

In this study, to verify the structural performance of the Composite Joint System (CJS) hybrid structural model, a cyclic load test was performed and evaluated and verified through the test. To verify the structural performance of the CJS hybrid structural systems' joint and evaluate the seismic performance, four three-dimensional real-size specimens were developed with three internal beam-column specimens and one external beam-column specimen. The three interior column specimens were classified by different methods of joining the upper column and lower column, and the same bonding method as the primary specimen was used for the exterior column. The structural performances in terms of drift, strength, and energy dissipation capacity were analyzed and compared based on the experimental results. From the displacement-based loading experiment, all specimens showed a lateral drift of 4.0% without any significant strength drop and stable energy dissipation capacity.

• Journal of Drive and Control
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• v.13 no.3
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• pp.53-66
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• 2016

New non-hybrid approaches to improve energy efficiency of construction machineries are reviewed in this paper. Hydraulic systems are classified into four classes according to Backe's classification and commercially promising new technologies are carefully chosen in each class. IMV, 3-Line CPR, Closed Circuit Displacement Control of Differential Cylinder, and Throttle-less Secondary Control are chosen as representative non-hybrid new technologies. Key principle of each technology is explained and representative references which run through each technology are selected. Advantages and weaknesses of each technology are discussed and compared from the view point of construction machinery manufacturers.

• Journal of Electrochemical Science and Technology
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• v.4 no.1
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• pp.19-26
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• 2013

Graphene/Ni-Al layered double hydroxide (LDH) hybrid materials were synthesized by a hydrothermal reaction. Hexagonal Ni-Al LDH particles nucleated and grew on graphene sheets, thus preventing restacking of the graphene sheets and aggregation of the Ni-Al LDH nanoparticles upon drying. Electrode made from the graphene/Ni-Al LDH hybrid materials showed a substantial improvement in electrochemical capacitance relative to those made with pure Ni-Al LDH nanoparticles. In addition, the graphene/Ni-Al LDH hybrid composite materials showed remarkable stability after 4000 cycles with over 100% capacitance retention. These materials are thus very promising for use in electrochemical capacitor electrodes.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.490-496
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• 2023

Unmanned aerial vehicles (UAVs) research is recently actively underway. Especially, fuel cell battery hybrid systems are widely used to overcome the limitations of continuous operation. However, fuel cell systems must be operated in combination with a battery due to their low specific output characteristics. Therefore, a hybrid power system model for UAVs is developed. The rule-based strategy is applied to the model to properly distribute power to batteries and fuel cells. As a result, the designed rule-based power distribution control operates UAVs while maintaining battery state of charge(SOC) at an appropriate level.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.3
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• pp.143-148
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• 2018

In this paper, the optimal fuzzy logic controller(FLC) for a hybrid renewable energy system(HRES) is proposed. Generally, hybrid renewable energy systems can consist of wind power, solar power, fuel cells and storage devices. The proposed FLC can effectively control the entire HRES by determining the output power of the fuel cell or the absorption power of the electrolyzer. In general, fuzzy logic controllers can be optimized by classical optimization algorithms such as genetic algorithms(GA) or particle swarm optimization(PSO). However, these FLC have a disadvantage in that their performance varies greatly depending on the control parameters of the optimization algorithms. Therefore, we propose a method to optimize the fuzzy logic controller using the teaching-learning based optimization(TLBO) algorithm which does not have the control parameters of the algorithm. The TLBO algorithm is an optimization algorithm that mimics the knowledge transfer mechanism in a class. To verify the performance of the proposed algorithm, we modeled the hybrid system using Matlab Tool and compare and analyze the performance with other classical optimization algorithms. The simulation results show that the proposed method shows better performance than the other methods.

• Journal of IKEEE
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• v.18 no.2
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• pp.228-233
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• 2014

In this paper, we propose a CMOS-memristor hybrid circuit that can perform 4-bit multiplication for future energy-efficient computing in nano-scale digital systems. The proposed CMOS-memristor hybrid circuit is based on the parallel architecture with AND and OR planes. This parallel architecture can be very useful in improving the power-delay product of the proposed circuit compared to the conventional CMOS array multiplier. Particularly, from the SPECTRE simulation of the proposed hybrid circuit with 0.13-mm CMOS devices and memristors, this proposed multiplier is estimated to have better power-delay product by 48% compared to the conventional CMOS array multiplier. In addition to this improvement in energy efficiency, this 4-bit multiplier circuit can occupy smaller area than the conventional array multiplier, because each cross-point memristor can be made only as small as $4F^2$.

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.195-202
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• 2022

Recently, the global automobile market is rapidly changing from internal combustion engine vehicles to eco-friendly vehicles including electric vehicles. Among eco-friendly vehicles, LPG vehicles are low in fine dust and are suggested as a realistic way to replace diesel vehicles. In addition, it is more economical than gasoline in its class, showing a cost-saving effect. In Korea, the business of converting gasoline into LPG is active. Research is being conducted to apply this to hybrid vehicles. In this study, the difference in energy consumption efficiency was analyzed when LPG fuel was applied by selecting a 2-liter GDI hybrid electric vehicle. The operation of the hybrid system according to various driving characteristics was confirmed by selecting the WLTC mode. As a result, it was confirmed that the BSFC was about 5% lower than that of gasoline fuel when using LPG fuel. This is due to the active operation of the motor while driving. Optimization is required as battery consumption increases from an energy perspective.