• Journal of Hydrogen and New Energy
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• v.23 no.6
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• pp.619-627
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• 2012

This study was experimentally investigated on the effects of spring stiffness applied to linear compressor chambers. The springs prevented piston head from colliding with engine cover, stored the kinetic energy and regenerated the kinetic energy. The linear engine has two combustion chambers and four compressor chamber. The combustion chamber bore size was 30 mm, maximum stroke was 31 mm and effective stroke volume was 25.45 cc respectively. The spring stiffness was varied such as 0, 0.5, 1.00, 2.9 and 14.7 N/mm. The linear engine was fueled with premixed LPG (propane 99%) and air by pre-mixture device. As an experimental result, The stroke, piston velocity and the piston frequency were increased by high spring stiffness. Also, thermal efficiency was grown. because the increased stroke made the higher compression ratio. In conclusion, electric power and efficiency were improved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.805-810
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• 2011

Recently, Use of Auxiliary power unit(APU) is increasing by growing demand for improvement of insufficient electric power and installation of emergency generation devices in military tracked vehicles and civil markets. And the trend is that the units are demanded for smaller size, lighter weight and higher output power, etc to suit consumer demands. To achieve these, it is essential to develop high performance system. Therefore, in this study, it was conducted in numerical analysis to investigate flow characteristics of rotor in APU generator. Also output performance of APU applied on the rotor is analyzed by experimental method. As the result, higher rotating speed of rotor caused high air flow rate at suction and it leads to linear increase of discharging flow rate. The maximum theoretical power was achieved at 12 $m^3$/min of flow rate and, at that time, output power of generator was about 7.825 kW. Also, it can be confirmed the stabilization of output performance is achieved in about 2 seconds by experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.683-688
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• 2018

Recently, the demand for electric energy has been increasing due to the spread of hybrid electric vehicles. In this study, to meet this demand, the ANSYS MAXWELL electromagnetic simulation system was used to compare the power generation characteristics of three types of suspension system that can generate electricity using energy harvesting technology. Next, the optimal design was determined for each model by using the commercial PIDO (Process Integration and Design Optimization) tool, PIANO (Process Integration, Automation and Optimization). We selected three design variables and constructed an approximate model based on the experimental design method through electromagnetic analysis for 18 experimental points derived from Orthogonal Arrays among the experimental design methods. Then, we determined the optimal design by applying the Evolutionary Algorithm. Finally, the optimal design results were verified by electromagnetic simulation of the optimum design result model using the same analysis conditions as those of the initial model. After comparing the power generation characteristics for the optimal structure for each linear generator model, the maximum power generation amounts in the 8pole-8slot, 12pole-12slot, and 16pole-16slot structures were 366.5W, 466.7W and 579.7W, respectively, and it was found that as the number of slots and poles increases, the power generation increases.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.870-873
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• 1988

AESOPS computer program is designed to find those eigenvalues of a linear dynamic system model which most strongly characterize oscillations between generator rotors. The low frequency oscillation actually occurred in October, 1986 in Korean Electric Power Corporation (KEPCO) System. 28 oscillation modes are identified through computer runs and two of them are calculated unstable in the case of the start of a pumped-storage unit. This program is considered to complement the conventional PSS/E stability program for the stability study of KEPCO system.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.66-69
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• 1993

We have developed a software package for the analysis of electric field distribution in human body. It includes the graphical finite element mesh generator, linear system of equations solver using sparse matrix and vector technique, and post-processor for the display of the results. This software package can be used in various research areas of biomedical engineering where we inject current or apply voltage to human body. The software package was developed on Macintosh II computer and the size of the model is only limited by the main memory.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.257-263
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• 2017

The following thesis researched into the characteristics of electrolytic ion water with different levels of electrical conductivity by adding NaCl into tap water which is for experimental use in multi-layered electrolytic ion water generator. Electrolytic ion water is generated by underwater electrolysis and the electrolysis generator has a simple structure, is easy to control and is highly utilized in industries. Electrolytic ion water is useful in many areas since it has a superior sterilizing power, has no possibility of secondary pollution itself as water and removes active oxygen. In the experiment, we used tap water with NaCl excluded and water with three different levels of electrical conductivity by changing NaCl concentration levels into three levels. The features of current and voltage in electrolytic ion water represented a form of quadric instead of the linear characteristic following ohm's law. As well, as the electric conductivity of water and applied voltage increased, we were able to generate much stronger acid water and alkali water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.19-24
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• 2020

The interest in renewable energy is increasing due to the depletion of fossil fuels. In particular, active research on wave power, which is highly predictable and abundant, is being conducted. The coaxial accelerator-type wave power generator used in this study was designed to improve the power generation efficiency by converting bidirectional linear motion into a rotational force. In an offshore engineering basin, waves were generated, and case tests were performed according to the wave period and wave height. The experimental results were verified by the theoretical method related to the frequency response, and the overall trend was confirmed to be consistent. These results are expected to be useful in estimating the power of wave generators and designing parameters to improve the efficiency of wave energy in the design stage before manufacturing. In addition, the manufacturer can predict the wave energy efficiency of wave generators, which can reduce the development time and cost by preventing trial and error processes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.619-624
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• 2015

Owing to miniaturization and low-power electronics, mobile, implanted, and wearable devices have become the main trends of electronics during the past decade. There has been much research regarding energy harvesting to achieve battery-free or self-powered devices. The optimal design problems of a double-pendulum kinetic-energy harvester from human motion are studied in this paper. For the given form factor, the weight of the harvester, and the known human excitation, the optimal design problem is solved using a dynamic non-linear double-pendulum model and an electric generator. The average electrical power was selected as the performance index for the given time period. A double-pendulum harvester was proven to be more efficient than a single-pendulum harvester when the appropriate parameters were used.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.62-97
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• 2000

Recently the research for utilization of waste heat produced from electric power plants, casting factories, heat treating factories or commercial are being afforded by the need for energy saving. The objective of this study is to develop a thermoelectric generation system which unused energy from close-at-hand sources such as garbage incineration heat and industrial exhaust etc. into electricity. This paper a thermoelectric technology on a optimum system design method and efficiency and cost effective thermoelectric element on order to extract the maximum power output from energy conversion of waste energy. It is shown that the longitudinal stresses of module contacted with two point constrained Al tubes could be released more than those with a one-point constrained.

• Solar Energy
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• v.18 no.4
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• pp.77-86
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• 1998

This study presents a so-called regenerative ER damper which does not require external power sources with aid of energy conversion from kinetic energy into electrical energy. The ER damper is manufactured by employing a rack and pinion mechanism which converts a linear piston motion to a rotary motion. This rotary motion is amplified by gears and subsequently activates a generator to produce an electrical energy. In order to demonstrate the efficiency of the mechanism, with respect to the frequency of the ER damper is investigated a generated electric voltage, which is amplified via a transformer prior to being applied to the ER damper. In addition, the damping force of the ER damper obtained by the regenerated voltage is evaluated.