• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.59-61
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• 1996

Fuel cell systems offer high efficiencies for energy conservation for transportation application. In addition, they can operate on alcohols and alternative fuels, while producing little or no noxious emissions. The goal of the fuel cell in transportation should be research and commercialization of fuel cell vehicles as economic competitors for internal combustion engine vehicle. The objective of the present study is to analyze feasibility of the fuel cell/battery combination as a power source for a bus.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.339-343
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• 2005

Hydrogen, as a future energy source, is thought as an alternative of fossil fuel in view of environment and energy security. Hydrogen has the properties of both fuel and electricity so that it can make the energy paradigm shift in the future. Therefore, researches on hydrogen in power system area are essential and urgent due to their huge effects on current paradigm. In this paper, the visions and technical challenges of hydrogen in power system are reviewed as energy storage, dispersed generation (DG), DC generator, and combined heat and power (CHP).

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.486-488
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• 2005

Hydrogen, as a future energy source, can be a good alternative of fossil fuel in view of environment and energy security. Hydrogen can be both fuel and electricity so that it will greatly change energy paradigm. Therefore, researches on hydrogen in power system area are essential and urgent due to their huge effects. In this paper, the importances and meanings of hydrogen in power system are reviewed as energy storage, DC generator, dispersed generation (DG), and combined heat and power (CHP). Technical challenges in hydrogen economy are also listed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.26-31
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• 2010

Finding sufficient supplies of clean energy for future is one of the society's most important challenges according to technologies. Alternative renewable energy source such as solar energy can be substituted for exceeding human energy need. The main factor affect to solar performance is a collective intensity. To enhance intensity, suitable equipment is a solar tracker. The solar tracker consists of sun point detector module, mechanical mechanism module with actuator and control system module. This paper presents sun point detector for solar tracker of daylight system. To evaluate the detecting accuracy, an experimental device is implemented. In experimental results, the accuracy of development system has under 0.11%/0.5deg.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.67-73
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• 2010

Finding sufficient supplies of clean energy for future is one of the society's most important challenges according to technologies. Alternative renewable energy source such as sun energy can be substituted for exceeding human energy need. The main factor affect to solar performance is a collective intensity. To enhance intensity, suitable equipment is a solar tracker. This paper presents design and evaluation of 1 layer polar motion control system for solar tracker suitable for building integrated system. To evaluation of tracking accuracy and adaptability, solar tracker with 64 links is implemented. In experimental results, the accuracy of tracking has under ${\pm}0.0287^{\circ}$ and the thickness has under 140mm.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.104-107
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• 2007

Among the alternative energy sources, the solar energy is recognized as an important energy source and its application is increasing. Especially in future, the hybrid solar energy generation system with battery will be widely used as an independent distributed power generation system. In this paper, a solar power hybrid home generation system using a contact-less power supply (CPS) that can transfer an electric power without any mechanical contact by using magnetic coupling instead of the power transfer by directly supplying the DC power to the home electric system is proposed. The proposed system consists of a ZVS boost converter, a half bridge LLC resonant converter and contact-less transformer.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.204-205
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• 2016

Human power is not dependent on other energy sources, but rather is a source of power for ourselves. Human power, the cleanest energy in the world, can be our future. Therefore, we should be interested in sustainable alternative energy. This paper solves the uneven power generation by utilizing the energy storage capability of the flywheel. Therefore, it improved the efficiency by 5% compared to the existing generation method. DC generators produce power at variable speed operation. The constant voltage was generated from the DC-DC converter to the duty ratio control. Therefore, the charging efficiency is improved by 5% by the constant voltage charging of the battery. And it can suppress the decrease of the output due to the circulation current due to the deviation of the output voltage in parallel operation of the pedal generator.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.1
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• pp.17-25
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• 2020

Ground-coupled heat pump (GCHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. Although some experimental and simulation works related to performance analysis of GCHP systems for commercial buildings have been done, relatively little has been reported on the performance evaluation of GCHP systems for school buildings. The purpose of this simulation study is to evaluate the performance of a hypothetical GCHP system for a school building in Seoul. We collected various data of building specifications and construction materials for the building and then modeled to calculate hourly building loads with SketchuUp and TRNSYS V17. In addition, we used GLD (Ground Loop Design) V2016, a GCHP system design and simulation software, to design the GCHP system for the building and to simulate temperature of circulating water in ground heat exchanger. The variation of entering source temperature (EST) into the system was calculated with different prediction time and then each result was compared. For 20 years of prediction time, EST for baseline design (Case A) based on the hourly simulation results were outranged from the design criteria.

• Journal of Korean Society of Forest Science
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• v.44 no.1
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• pp.43-47
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• 1979

Increased demand for wood products and recent energy crisis have stimulated much attention over the world to the concept of intensive forestry management systems. This shows great potential of increasing biomass yields. Biomass probably will not be a major source to solve the whole problems of fiber and energy shortage but as an alternative source it will, in part, help meet the remarkable demand. In Korea, the systems are not only feasible because of available land areas, many appropriate tree and existing forestry techniques already available, but also urgently needed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.561-569
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• 2006

Because of the trend of deregulation, power industry is going through an unprecedented transformation in North America and Europe, and there are a host of acquisitions and mergers by the private sector to position themselves to take advantage of new business opportunities. Deregulation has accelerated the development of smaller generators and fuel cells will gradually become more attractive to mainstream electricity users as they improve in capability and decrease in cost. Fuel Cell technology is surveyed and the potential of using fuel cell as a distributed generation source is presented. This paper recommends the fuel cell power plants as alternative energy sources for distributed generation in Jeju Island, Korea. This will help in increasing fuel efficiency, at least double the current thermal plants', increasing the reliability of power supply, reducing the dependency on the HVDC link, providing quality power to the growing infrastructure, and maintaining clean air in meeting the free-trade international island.