• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.4
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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.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.183-187
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• 2008

This paper describes a power control scheme to improve the performance of a fuel cell battery hybrid power source for residential application. The proposed power control scheme includes a power control strategy to control the power flow of the fuel cell hybrid power system and a digital control technique for a front-end dc-dc converter of the fuel cell. The power control strategy enables the fuel cell to operate within the high efficiency region defined by the polarization curve and efficiency curve of the fuel cell. A dual boost converter with digital control is applied as a front-end dc-dc converter to control the fuel cell output power. The digital control technique of the converter employs a moving-average digital filter into its voltage feedback loop to cancel the low frequency harmonic current drawn from the fuel cell and then limits the fuel cell output current to a current limit using a predictive current limiter to keep the fuel cell operation within the high efficiency region as well as to minimize the fuel cell oxygen starvation.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.536-538
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• 2018

This paper introduces an enhanced interleaved (IL) PFC (Power Factor Correction) boost converter typed 650V Intelligent Power Module (IPM), which is fully optimized hybrid IGBT converter modules; Silicon (Si) IGBT and Silicon Carbide (SiC) diode, for up to 10kW HVAC (Heating, Ventilation, and Air Conditioning) systems. It utilizes newly developed $4^{th}$ Generation Field Stop (FS) trench IGBTs, $EXTREMEFAST^{TM}$ anti-paralleled diodes, SiC Junction Barrier Schottky (JBS) diodes, Bridge rectifiers, Multi-function LVIC, and Built-in thermistor provide good reliable characteristics for the entire system. This module also takes technical advantage of DBC (Direct Bonded Copper) substrate for the better thermal performance. It is shown that the Si IGBT/SiC diode hybrid IL PFC module can achieve excellent EMI performance and greatly enhance the power handling capability or switching frequency of various applications compared to the Si IGBT/Diode. This paper provides an overall description of the newly developed 650V/50A Hybrid SiC IL PFC IPM product.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.57-65
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• 2021

This paper explains a DMFC-Lithium Battery hybrid system applied to a forklift. A conventional Lead Acid battery forklift has several problems: long charging times, short operation times, and frequent battery replacements. As a result, hydrogen-powered forklifts are replacing Lead acid battery-powered forklifts due to their shorter refueling time and longer operation times. However, in doing so, we are confronted with the problem of a high hydrogen refueling infrastructure. A Direct Methanol Fuel Cell (DMFC), on the other hand, is an eco-friendly generator that directly converts the chemical energy of methanol into electricity. In general, DMFC is regarded as a small power generator under kW power. In this paper, a DMFC-Battery hybrid system is applied to a 1.5 ton forklift by increasing the power output of the DMFC stack and utilizing the high charge-discharge characteristics of a lithium battery.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.231-235
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• 2008

Thyristor rectifiers are still the preferred choice for large magnet power supplies. However, large harmonic voltages, resulting in large current ripple, and slow dynamic response are major drawbacks of these converters. Joos presented a topology and a control technique for a hybrid large-power high-precision magnet power supply in 1996. The system consists of a phase controlled rectifier (PCR) connected in series with a high-frequency PWM converter. This paper improves the power circuit of the PWM converter using interphase transformer. Simulation result proves effect of the proposed system.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.293-295
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• 2001

In this paper, a control algorithm of a stand-alone type photovoltaic/wind/diesel hybrid power system for operation in a remote island, is proposed in detail. Power controllers are used to combine two different power outputs of photovoltaic and wind-power generations into DC output, which is converted into AC power to meet load while charging the storage battery for later use. In the event that the whole power load cannot be met by photovoltaic and wind power only, power stored in the battery cell is supplied and if even this power run out, diesel generator will be applied. Certain portion of diesel power is used to cover the load and the other to charge the battery.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.40-50
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• 2012

The electrification of the waste heat of stack is necessary to enhance the efficiency of fuel cell system. For this purpose, the hybrid SOFC/GT/ST system is suitable. The purpose of this work is to predict the performance of methane fueled SOFC/GT/ST hybrid power system and to analyze the influence of operating temperature of stack, current density of stack, and gas turbine pressure ratio. According to the analysis, it is proved that the SOFC/GT/ST hybrid system suppress the rapid decrease in efficiency and lead to the significant improvement of efficiency as compared with SOFC system.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.99-120
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• 2017

In SS branch of Korea District Heating Corporation, Combined Heat & Power power plant with 99MW capacity and 98Gcal / h capacity is operated as a district electricity business. In this region, it is difficult to operate the generator due to the problem of surplus heat treatment between June and September due to the economic recession and the decrease in demand, so it is urgent to develop an economical energy new business model. In this study, we will develop an optimized operation model by introducing a renewable energy hybrid system based on actual operation data of this site. In particular, among renewable energy sources, fuel cell (Fuel Cell) power generation which can generate heat and electricity at the same time with limited location constraints, photovoltaic power generation which is representative renewable energy, ESS (Energy Storage System). HOMER (Hybrid Optimization of Multiple Energy Resources) program was used to select the optimal model. As a result of the economic analysis, 99MW CHP combined cycle power generation is the most economical in terms of net present cost (NPC), but 99MW CHP in terms of carbon emission trading and renewable energy certificate And 5MW fuel cells, and 521kW of solar power to supply electricity and heat than the supply of electricity and heat by 99MW CHP cogeneration power, it was shown that it is economically up to 247.5 billion won. we confirmed the results of the improvement of the zone electricity business condition by introducing the fuel cell and the renewable energy hybrid system as the optimization process model.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.189-194
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• 2014

Due to the increasing of power consumption, it is difficult to construct accurate prediction model for daily peak power demand. It is very important work to know power demand in next day for manager and control power system. In this research, we develop a daily peak power demand prediction method based on hybrid type composed of AR and Neuro-Fuzzy model. Using data sets between 2006 and 2010 in Korea, the proposed method has been intensively tested. As the prediction results, we confirm that the proposed method makes it possible to effective estimate daily peak power demand than conventional methods.

• Advances in Energy Research
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• v.3 no.1
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• pp.59-70
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• 2015

In India, continuous production of electricity and sweet/potable water from Solar power and desalination plant plays a major role in the industries. Particularly in Copper industry, Solar power adopts Solar field collector combined with thermal storage system and steam Boiler, Turbine & Generator (BTG) for electricity production and desalination plant adopts Reverse osmosis (RO) for sweet/potable water production which cannot be used for long hours of power generation and consistency of energy supply for industrial processes and power generation cannot be ensured. This paper presents an overview of enhanced technology for Solar power and Desalination plant for Copper industry making it continuous production of electricity and sweet/potable water. The conventional technology can be replaced with this proposed technique in the existing and upcoming industries.