• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.55-59
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• 2005

In this paper, a new drive system(SHS) for hybrid electric vehicle is proposed. As dual rotor hybrid electric vehicle using planetary gearsets, the SHS has the advantages of both series and parallel systems. The output speed and torque of SHS can be determined at specific point regardless of the engine's operating point. When the size of generator which is used in SHS is same as in THS, the SHS has more activities of engine control due to the ability that is operated in lower speed range. To maximize the performance of system, we carried out optimization for the three parameters that are engine, motorl and motor2. As the result of the optimization, we confirmed the SHS is more preferable to THS in fuel consumption and acceleration area.

• Journal of Information Processing Systems
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• v.15 no.2
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• pp.422-432
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• 2019

A hybrid kernel function of support vector machine is proposed to improve the classification performance of power quality disturbances. The kernel function mathematical model of support vector machine directly affects the classification performance. Different types of kernel functions have different generalization ability and learning ability. The single kernel function cannot have better ability both in learning and generalization. To overcome this problem, we propose a hybrid kernel function that is composed of two single kernel functions to improve both the ability in generation and learning. In simulations, we respectively used the single and multiple power quality disturbances to test classification performance of support vector machine algorithm with the proposed hybrid kernel function. Compared with other support vector machine algorithms, the improved support vector machine algorithm has better performance for the classification of power quality signals with single and multiple disturbances.

• New & Renewable Energy
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• v.3 no.2 s.10
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• pp.60-67
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• 2007

This paper describes the design and integration of the wind-fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), hydrogen storage tank and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. Hydrogen may be produced and stored in high pressure tank by hydrogen gas booster system. Wind conditions are changing with time of day, season and year. So, wind power is a variable energy source. The main purpose with these WT-FC hybrid system is to store hydrogen by electrolysis of water when wind conditions are good and release the stored hydrog en to supply the fuelcell when wind is low.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.9
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• pp.757-762
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• 2014

A solar heat and power hybrid system can simultaneously generate electricity and thermal energy. In this study, several experiments were carried out with a solar heat and power hybrid unit. Then, a method to increase the photovoltaic efficiency and amount of thermal energy was suggested based on a comparative analysis. The experiment was conducted using only the photovoltaic system as a reference case, with the photovoltaic-thermal air system as a hybrid case. A numerical increase in the photovoltaic efficiency per $1^{\circ}C$ was suggested based on a comparative data analysis of these two cases. In this experiment, the surface temperature on the air hybrid system was $13.52^{\circ}C$ lower than that in the reference case, and the photovoltaic efficiency was increased by 5.09. The amount of thermal energy produced was 15.69 Wt per $1^{\circ}C$ difference between the ambient and outlet temperatures. In this paper, therefore, a photovoltaic efficiency increase of 0.34 per $1^{\circ}C$ is proposed for the air hybrid system based on the analysis of the experimental data.

• New & Renewable Energy
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• v.1 no.1 s.1
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• pp.32-36
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• 2005

We studied the optoelectronic properties of hybrid solar cells formed by mixing cadmium sulfide [CdS] nanorods with a conjugated polymer, poly-2-methoxy, 5-[2'-ethy[hexyloxy]-1,4-p-phenylenevinylene[MEH-PPV]. CdS nanorods were grown vertically on Ti substrates by electrochemical deposition through a porous alumina template. Absorption spectrum of the composite layer was the same as the superposition of the absorption spectrum of each individual layer. The photoluminescence signal from MEH-PPV film was reduced as a result of the mixing. The energy conversion efficiency of MEH-PPV improved from $0.0012\%$ to about $0.60\%$ when combined with the vertically aligned CdS nanorods.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.115-115
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• 2008

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.574-585
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• 2015

This paper aims to improve the performance of conventional direct torque control (DTC) drives proposed by Takahashi by extending the idea for 5-level inverter. Hybrid cascaded H-bridge topology is used to achieve inverter voltage vector composed of 5-level of voltage. Although DTC is very popular for its simplicity but it suffers from some disadvantages like- high torque ripple and uncontrollable switching frequency. To compensate these shortcomings conventional DTC strategy is modified for five levels voltage source inverter (VSI). Multilevel hysteresis controller for both flux and torque is used. Optimal voltage vector selection from precise lookup table utilizing 12 sector, 9 torque level and 4 flux level is proposed to improve DTC performance. These voltage references are produced utilizing a hybrid cascaded H-bridge multilevel inverter, where inverter each phase can be realized using multiple dc source. Fuel cells, car batteries or ultra-capacitor are normally the choice of required dc source. Simulation results shows that the DTC drive performance is considerably improved in terms of lower torque and flux ripple and less THD. These have been experimentally evaluated and compared with the basic DTC developed by Takahashi.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.232-232
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• 2006

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.958-963
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• 2012

Characteristics of off-grid hybrid renewable energy sources for high mountain villages are discussed. Considering reliability of electric power generation, Photovoltaic (PV)-wind hybrid and PV-hydro hybrid system are suggested. Connecting two or more villages with these hybrid systems, an extended hybrid off-grid can be formed. Sustainability of entire system is important in design of off-grid system, and income generation of the village people using the electricity should be considered.

• New & Renewable Energy
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• v.17 no.3
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• pp.1-7
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• 2021

The Korean government announced various energy policies, such as the to reduce 37% of the business-as-usual (BAU) greenhouse gas emissions by 2030. The policies aim to increase the renewable electricity generation ratio to 20% by 2030. PVT is a hybrid technology, which combines photovoltaic (PV) and solar collectors. It is capable of generating electricity and thermal energy simultaneously. It has a great potential to be used as a renewable and clean solar energy. However, there exists a shortage of space for the installation of PVT systems in Korea. To overcome this, in this paper proposes four types of soundproof wall PVT air channels, which were designed and optimized, based on the CFD (Computation Fluid Dynamic) analysis results. The thermal energy generation for multiple PVT units connected in series and pressure drop sensitivity were analyzed, depending on inlet velocity.