• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.163-169
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• 2006

A Life Cycle Assessment (LCA) study was carried out to identify and improve the environmental aspects associated with the present incineration system of spent Li-ion batteries (LIBs) in Korea. The environmental impact associated with the landfill of the incineration ash was also assessed in this study, while so far it was excluded in most studies. It was found out that the $CO_{2}$ emission from the electricity generation as well as the incineration process and heavy metals emissions to air and water accounted for about 90% of total environmental impacts. In particular, the effect of the emission of heavy metals were dominant. In oder to improve the current incineration system environmentally, it is needed to incinerate the wastes like spent LIBs which contained relatively high portion of heavy metals separately from other combustible wastes. On the other hand, the effect of the landfill of ash after incineration was insignificant since the ash from the incineration process was chemically stable.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.237.1-237.1
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• 2010

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Ocean contains energy in form of thermal energy and mechanical energy: thermal energy from solar radiation and mechanical energy from the waves and tides. The current paper looks at generating power using waves. The primary objective of the present study is to maximize the primary energy conversion (first stage conversion) of the base model by making some design changes. The model entire consisted of a numerical wave tank and the turbine section. The turbine section had three components; front guide nozzle, augmentation channel and the rear chamber. The augmentation channel further consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. Different front guide nozzle configuration and rear chamber design were studied. As mentioned, a numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet. The inlet which was modeled as a plate wall which moved sinusoidally with the general function, $x=asin{\omega}t$. In addition to primary energy conversion, observation of flow characteristics, pressure and the velocity in the augmentation channel, rear chamber as well as the front guide nozzle are presented in the paper. The analysis was performed using the commercial code of the ANSYS-CFX. The base model recorded water power of 29.9 W. After making the changes, the best model obtained water power of 37.1 W which represents an increase of approximately 24% in water power and primary energy conversion.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.121-127
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• 2016

We propose a algorithm to calculate power factor of fundamental waveform in an environment where the voltage and current have been distorted by harmonics. In the proposed power factor computation algorithm, voltage and current are converted to rotating DQ reference frame, and power factor is calculated from active power and reactive power. We compare the proposed method with the conventional power factor measurement method as mathematically. In a condition that voltage and current are distorted by harmonics, the proposed method accurately measure the power factor of fundamental wave, and it is confirmed by simulation using MATLAB. If the proposed power factor measurement method is applied to an automatic power factor control system, a power factor compensation performance can be maximized in harmonic distortion environment. As a result, it is possible to reduce electricity prices, reduce line loss, increase load capacity, ensure the transmission margin capacity, and reduce the amount of power generation.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.91-98
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• 2017

Due to climate change, countries around the world are actively investing in renewable energy, reducing fossil fuel use. 23.7% of world electricity is supplied by renewable energy. As the technology continues to develop, it is in a level to compete in terms of power generation cost, and investment conditions are improving. However, investment in renewable energy projects is not easy. This study analyzed trends of domestic and international researches on economics assessment applying real options analysis to investment decisions of hydro, solar, and wind power projects, which account for a large portion of renewable energy. This study provides (1) the difference between the traditional economic method and the real options analysis, (2) the application process, and (3) the uncertainty elements and option type of the renewable energy project presented by many studies. The real options analysis is suitable for the detailed investment strategy by considering the uncertainties of the renewable energy project and applying the option to improve the profit or to avoid the risk.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.1
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• pp.45-51
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• 2015

In this study, continuous microbial fuel cells (MFCs) were operated using non-precious metal catalysts such as iron(II) phthalocyanine (FePc) and cobalt tetramethoxyphenylporphyrin (CoTMPP)) as alternative cathode catalysts for platinum. To evaluate MFCs performance, operational conditions of organic loading rate (OLR) (0.5~3 g COD/L/d) and hydraulic retention rate (HRT) (0.25~1 day) were changed. Power density of MFCs were determined by cathode electrode performance. The maximum power density was $3.3W/m^3$ with platinum at OLR 3 g COD/L/d. Given each HRTs at 1 g COD/L/d, FePc showed to be a better alternative for platinum than CoTMPP because the power density of MFC with FePc was similar to that of MFC with platinum. CoTMPP catalyst, however, showed the lowest power density due to increase of internal resistance during continuous operation.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.95-101
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• 2009

The generator for gas turbine power generation consists of the rotor which generates magnetic field, the winding coil which is the path for the field current and the wedge and retaining ring which prevents the radial movement of the coil. Relatively severe deformation was observed at the coil end section during the inspection of the generator for peaking-load operation, and the thermal-electricity and the centrifugal force were evaluated by the simple modeling of the windings to find the cause. But the simulation stress was not sufficient to induce the coil plastic deformation. The analysis result seems to be applicable to the base-load generators which runs continuously without shut down up to a year, but there had been more deformation than simulated for the generator which is started up and shut down frequently. The cause of the coil deformation was the restriction of the expansion and shrinkage. The restriction occurs when the winding coil shrinks, and the stress overwhelms the yield stress and cause the plastic deformation. The deformation is accumulated during the start-ups and shut-downs and the thermal growth occurs. The factors which induce the coil restriction during the expansion and shrinkage should be reduced to prevent the unallowable deformation. The resolutions are cutting off the field current earlier during the generator shut-down, modifying the coil end section to remove the stress concentration and making the insulation plate inserted between the coil end section and the retaining ring have the constant thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.338-338
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• 2009

To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, noncontact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. We investigated the high pretilt angle effects on electro-optical properties of ion beam (IB)-irradiated liquid crystal cells. on a blended polymer surface. High pretilt angle of liquid crystals IB-irradiated on a blended polymer surface including such as 5% and 10% of homeotropic polymer contents can' be achieved. The threshold voltages of IB-irradiated twisted nematic (TN) cells on a blended polymer surface decrease with increasing the pretilt angle. Also, the rising time of IB-irradiated TN cells decreases with increasing the pretilt angle. However the decay time of IB-irradiated TN cells increases with increasing the pretilt angle. Consequently, the electro-optical properties of IB-irradiated TN cells depend strongly on the pretilt angle in a blended polymer surface.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.86-91
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• 2002

Solid Oxide Fuel Cells (SOFC) are of great interest of next generation energy conversion system due to their high energy efficiency and environmental friendliness. The basic SOFC unit consists of anode, cathode and solid electrolyte. Among these components, anode plays the most important role for the oxidation of fuel to generate electricity and also behaves as a substrate of the whole cell. It is normally requested that the anode materials should have the high electrical conductivity and gas permeability to reduce the polarization loss of the cell. In this study, the effect of pore former on the microstructure of anode substrate was investigated and thus on the electrical conductivity and the gas permeability. According to the results, microstructure and electrical conductivity of anode substrate were greatly influenced by the shape of pore former and especially by the anisotrpy of the pore former. The use of anisotropic pore former is supposed to deteriorate the cell performance by which the electrical conduction path is disconnected but also the effective gas diffusion path for the fuel is reduced.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.293-299
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• 2012

The thermodynamic efficiency characteristics of R245fa and water as working fluids have been analyzed for the electricity generation system applying the Rankine cycle to recover the waste heat of the exhaust gas from a diesel engine for the propulsion of a large ship. The theoretical calculation results showed that the cycle, system, and total efficiencies were improved as the turbine inlet pressure was increased for R245fa at a fixed mass flow rate. In addition, the net work rate generated by the Rankine cycle was elevated with increasing turbine inlet pressure. In the case of water, however, the maximum system efficiencies were demonstrated at relatively small ratios of mass flow rate and turbine inlet pressure, respectively, compared to those of R245fa. The optimized values of the net power of the cycle, system efficiency, and total efficiency for water had relatively large values compared to those of R245fa.

• Journal of Energy Engineering
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• v.19 no.3
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• pp.188-194
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• 2010

Direct Carbon Fuel Cell(DCFC), unlike gas turbines or engines, is a kind of fuel cell which directly generates electricity by electrochemical reaction from a carbon fuel. The advantages of DCFC are higher efficiency and lower emission in comparison with existing power generation facilities. In this study, the effects of CO and $CO_2$ on theoretical potential are examined using the thermodynamic equilibrium method, and the dependence of product on operating temperature is examined via two dimensional CFD method. As a result, when the reaction of CO production (Boudouard reaction) considered, theoretical potential is higher than that in only $CO_2$ reactions, and its value increases as temperature increases. Two dimensional results of computational fluid dynamics(CFD) confirm that the Boudouard reaction becomes more important to be considered as temperature increases and inert gas affects the equilibrium composition of the Boudouard reaction.