• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.279-282
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• 2015

Energy Technology Perspectives (ETP) has provided the current status of energy system, technology developments and external events that have changed ETP scenario since 2006. The three scenarios are presented in four different fields (power generation, transport, industry, building). Energy efficiency improvement of energy system and the new system that can solve the increasing energy demand and the emissions are introduced. The activities on IEA/ECERC delegation of Korea will be also reported in this presentation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.8
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• pp.2170-2187
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• 2023

The general interference is the imperative trouble for simultaneous wireless information and power transfer (SWIPT) system. Although interference has bad influences on the performance of the system, it carries energy simultaneously. In this paper, the energy-constrained relay of the SWIPT system needs to spend much time on energy collecting (EC) in the information transmission (IT) period. Therefore, we propose the scheme of interference signal energy collecting (ISEC) when the interference is strong, and the SWIPT system does not carry out IT. The relay of the system continues to collect energy and stores it until the interference has minimal impact on IT. Then the system performs IT. We divide the collected interference energy equally into several parts, and each IT block receives one part. The proposed scheme is appealing because it can reduce the time of EC in IT period to make the relay spends more time forwarding the received signal in order to improve the performance of the system throughput. Furthermore, we propose a time-switching (TS) protocol based on EC at the relay. And it allows the relay forwarding signal at an appropriate power. Under the protocol, the time of EC can be flexible according to the forwarding power that we give so that the collected energy can be used more efficiently. We give the expressions of the system throughput according to the proposed scheme and protocol. Moreover, the influence of the interference power on the system throughput is also studied.

• Korean System Dynamics Review
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• v.15 no.2
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• pp.51-74
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• 2014

Over the past few years Korea has achieved rapid economic growth, while the deepening polarization of income has negatively affected Korea economy and society. It can be the reason of this negative effect on economy that the increased income by the economic growth has not been distributed socially, but overly focused on one part of social class. One of the important and powerful solution of social polarization could be the strengthening of the income distribution. In these circumstances, the social interest and discussion on the universal welfare system and on the basic income as the means of income redistribution have been increasing. In this study, a system dynamic analysis was conducted to find how an universal cash payment as basic income providing cash benefits impacts on the promotion of consumption in private sector, of local jobs and of local economic organizations. Recently, the poor energy consumption ability of energy poverty became one of the social problems. Also it was analysed how an energy payment-in-kind as basic income influences on the energy consumption of the region, the energy production capacity, the promotion of local energy. The universal cash payment and energy payment-in-kind as the basic income policy showed similar and positive effects on the local economy system and on the local energy system respectively.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.43-48
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• 2009

In this study, through case studies, solar energy systems were coordinated with architectural plan elements and the others in apartment complex, and the energy performance was evaluated quantitatively through computer simulation PVSYST and RETScreen. As a results, in plan process of the application of solar energy systems in apartment complex, solar energy system should be considered as not only energy reducing technical element but also part of architectural plan element. And it must be considered with architectural plan elements, composition methods, energy storage methods, technical elements from the early basic plan stage. Photovoltaic system was installed on the wall facing the south and rooftop. The energy ratio of electric load was shown to be 5.5%. The result showed 7.2% when adding it to shading device additionally, and 6.4% in case of putting extra translucent module on windows. Active solar collecting system was applied on roof with the angle of 45. Maximum number of solar collector was 10 in a row, and the total solar collecting area was $915.00m^2$. The energy ratio of domestic water heating load by active solar hot water system is shown to be 11.4%.

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.22-26
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• 2011

As new one of superconducting power supplies, we proposed an HTS flux pump utilized a solar energy system. As an eternal electric energy can be converted by the solar system, the solar energy system is promisingly applied as an energy source in the power applications. Especially, since the solar energy system played a role in conventional utility power, total power consumption of the flux pump system are provided by solar energy. That means its operating efficiency is remarkably improved compared with developed flux pumps. A solar energy system is comprised of solar panel, photo-voltaic (PV) controller, converter and battery. The HTS flux pump consists of an electromagnet, two thermal heaters and a Bi-2223 magnet. In this paper, we describe the possibility the fusion technology between superconducting power supply and solar energy system. As a fundamental step, the fabrication, structure and experimental results are explained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2048-2053
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• 2011

The aim of this paper is to propose an energy harvesting system by converting mechanical energy of revolving door into electrical energy. The method of energy harvesting system is discussed on two methods: one is the energy-harvester using gear shaft coupling system, and the other is the energy-harvester using spiral spring system. The former is generated by coupling the shaft of rotating door with generator system, while the latter is generated by connecting end-effector of door with the string of generator system. We present the experimental results for two developed energy-harvester. Finally, a comparison between these results is presented to show the validity of energy-harvester.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.596-604
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• 2005

This paper presents the work on evaluating the LCC (Life-Cycle Cost) of a heat pump system as unutilized energy system. The river water as an unutilized energy source was used for the heat source of heat pump system. LCC analysis is a concrete method for evaluating the economical efficiency of energy facilities of building. The present case study shows an example of adequate use of the LCC analysis on a heat pump system and conventional gas boiler and refrigerator for building heat supply. A life cycle of 20 years was used to calculated net present value of energy cost. Over a 20 year life cycle, the energy cost could be reduced by 612 million won if a heat pump system were used instead of a conventional boiler and an absorption refrigerator.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1511-1519
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• 2014

The objective of this paper is to propose a modelling of a small compressed air energy storage system, which drives an induction generator based on a field-oriented control (FOC) principle for a renewable power generation. The proposed system is a hybrid technology of energy storage and electrification, which is developed to use as a small scale of renewable energy power plant. The energy will be transferred from the renewable energy resource to the compressed air energy by reciprocating air compressor to be stored in a pressurized vessel. The energy storage system uses a small compressed air energy storage system, developed as a small unit and installed above ground to avoid site limitation as same as the conventional CAES does. Therefore, it is suitable to be placed at any location. The system is operated in low pressure not more than 15 bar, so, it easy to available component in country and inexpensive. The power generation uses a variable speed induction generator (IG). The relationship of pressure and air flow of the compressed air, which varies continuously during the discharge of compressed air to drive the generator, is considered as a control command. As a result, the generator generates power in wide speed range. Unlike the conventional CAES that used gas turbine, this system does not have any combustion units. Thus, the system does not burn fuel and exhaust pollution. This paper expresses the modelling, thermodynamic analysis simulation and experiment to obtain the characteristic and performance of a new concept of a small compressed air energy storage power plant, which can be helpful in system designing of renewable energy electrification. The system was tested under a range of expansion pressure ratios in order to determine its characteristics and performance. The efficiency of expansion air of 49.34% is calculated, while the efficiency of generator of 60.85% is examined. The overall efficiency of system of approximately 30% is also investigated.

• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.107-119
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• 2002

A review on the papers published in the Korean Journal of Solar Energy between 2000 and 2002 has been done. Focus has been put on current status of research in the aspect of Insolation. Solar Collector and Storage System, Solar Heating and Cooling System, Solar Cell and Lighting System, Active and Passive Solar Building, Heat Transfer in Solar Energy and Natural Energy. The conclusions are as follows. 1) Many studies on Insolation were conducted to optimize the usage of Solar Energy. 2) A review of the recent studies on solar thermal shows that there were many papers on solar collector and storage system. However, studies on the HVAC system using solar energy were relatively insufficient. 3) To produce high efficient solar cell. various experimental and numerical papers were published. However studies on control system, solar cell and lighting were seemed to be insufficient. 4) Studies on using solar energy in passive solar buildings were widely carried out, however, studies based on synthetic analysis of buildings and BIPV were insufficient. 5) Studies on heat transfer were mainly about heat exchanger, performance of heat pipe and multi air conditioner. 6) Studies on energy resources except for solar energy, such as hydraulic power and wind power etc. were very few.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1339-1346
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• 2011

This paper is developed to demand management scenario of energy consumption efficiency improvement, electricity generation efficiency improvement, network efficiency improvement, change of distribution ratio, movement of energy source, change of heating system, put of CHP to quantitatively assess to impact on energy use of demand management at the national level. This scenario can be applied Energy System Management model was developed based on Energy Balance Flow. In addition, effect analysis through built demand management scenario was quantitatively evaluated integrated demand management effectiveness of energy cost saving, CO2 emission reduction and energy savings of national level by calculating to primary energy source usage change in terms of integration demand management effect more often than not a single energy source separated electricity, heat and gas.