• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.364-371
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• 2005

Fuel cell systems(FCS) have a financial and environmental advantage by providing electricity at a high efficiency and useful heat. For use in a residence, a polymer electrolyte fuel cell system(PEFCS) with a battery pack and a hot water storage tank has been modelled and simulated. The system is operated without connection to grid line. Its electric conversion efficiency and heat recovery performance are highly dependent on operation strategies and also on the seasonal thermal and electric load pattern. The output of the fuel cell is controlled stepwise as a function of the state of the battery and/or the storage water tank. In this study various operation strategies for cogeneration fuel cell systems are investigated. Average fuel saving rates at different seasons are calculated to find proper load management strategy. The scheme can be used to determine the optimal operating strategies of PEFCS for residential and building applications.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.20-25
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• 2021

In the background of the rapid development of the IoT, smart home work is becoming more and more important to each science and technology company. Smart home provides a safe, comfortable, high-quality, high-performance smart home living space compared to general homes, and at the same time It is responding to the low-carbon, eco-friendly global trend. Growth drivers driving the smart home market are increasing the number of Internet users, increasing disposable income in developing countries, increasing the importance of remote home monitoring, and increasing the need for energy saving and low carbon. In 2013-2014, Xiaomi launched a series of smart routers and smart home hardware devices. In 2015, it announced the latest product of the Xiaomi Ecological Chain, the "Smart Home Package," and in 2016 launched the MIJIA brand to invest in various smart product companies. In 2017, Xiaomi announced a plan to build an open smart hardware MIOT platform. We investigated the management strategy of Xiaomi home smart service based on IOT. The management strategy was divided into cost lead strategy, differentiation strategy of Xiaomi home service, and AIOT strategy of Xiaomi smart home.

• KIEAE Journal
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• v.14 no.1
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• pp.59-66
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• 2014

G-SEED aims for establishing green environmental building with energy saving and has started for evaluating with multi-residential complex in 2002 by the Ministry of Land, Infrastructure & Transport (MOLIT) and the Ministry of Environment to develop the current 10 building types and new & existing building types to be applied. Since G-SEED has been developed for more than 10 years, the strategy of globalization is needed with constant review itself and comparison between other assessments to understand current situation from the global perspectives. This study draws similarities and differences of G-SEED and LEED criteria by the comparison from re-constructed LEED criteria based on G-SEED. "Energy & Pollution" is the most concerned category in both assessments as the result of analysis on category rates. Next concerns are "Material & Resources", "Indoor Environment" and "Water Management". The unique categories in both criteria are "Ecological Environment" in G-SEED and "Innovation & Design Process" in LEED. The conclusion of this research is that two assessments are organized at different locations and with different strategies for developing green building but there are common concerns such as energy saving, material use, indoor environment. As a result, it is expected to use fundamental data for developing G-SEED for global standard.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.753-764
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• 2015

Among several types of energy saving smart window technologies, the leader, the dynamic EC (electrochromic) window one needs integrated PV (photovoltaics), to minimize expensive electrical wiring as well as to obviate the need for external energy. Self-powered smart windows were reviewed according to PV types used. DSSCs (dye sensitized solar cells) were found to be compatible with EC cells, to have several categories of next generation smart windows such as PECCs (photoelectrochromic cells), PVCCs (photovoltachromic cells), EC polymer PECCs. In addition silicon solar cells and third generation solar cells were investigated. They are summarized in a table showing their advantages and disadvantages respectively for a fast comparison. The strategy to expedite the commercialization of these next generation smart windows includes developing retrofit smart window coverings for use on flexible polymer substrates adhered to the inside surface of a window and easily replaced after use for upto 10 years.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.31-37
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• 2007

The fuzzy control algorithm for HVAC system has been developed for minimizing energy consumption while maintaining the comfort of indoor thermal environment in terms of the environmental variables such as time varying indoor cooling load and outdoor temperatures. The optimal set-points of control parameters with fuzzy control are supply air temperature, chilled water temperature and condenser temperature. This study has been done by using TRNSYS program in order to analyze the HVAC system response. As a result, the fuzzy control algorithm with PID algorithm shows good energy performance in comparison with conventional one.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1645-1655
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• 2016

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zero-steady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

• KIEAE Journal
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• v.14 no.2
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• pp.37-46
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• 2014

University buildings are energy-guzzling facility that consume more than 10,000TOE within a campus annually. Even the consumption is on an upswing trend. Behind such high consumption are there cheap power rates for education facility, lack of high-efficiency equipment and ever-increasing use of various information equipment. Being keenly aware that greenhouse gas emission increases due to such rise of energy consumption, the present study carried out a case study. In the case study, the study chose the buildings of E university from top 10 universities that consume energy most in Seoul and examined the current status of their energy consumption and greenhouse gas emission. And then it set the reduction target of greenhouse gas by year. Putting aside a middle and long-termed strategy for later endeavor, it first established the 1st year's implementation plan (2014) for energy saving and greenhouse gas reduction with limited budget and according to greenhouse gas reduction target. The plan is specified as follows. Targets for energy saving are mainly divided into two sectors: machine equipment and electric equipment. 7 ideas were proposed. Three ideas to improve machine equipment are to replace with high-efficiency boilers and chillers and to adjust the position of the cooling tower. By doing so, it was estimated that energy could be saved by 176.34TOE in total and greenhouse gas could be reduced by 370.771t$CO_2$-eq. Four ideas to improve electric equipment include the replacement with LED lights, LED emergency lights and high-efficiency motors and the installation of motion sensors. It was calculated that such replacement could conserve 1,076.08TOE (electric energy) and reduce 2,181.420t$CO_2$-eq (greenhouse gas).

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1487-1489
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• 1999

The power demand has increased the groth of industry and improvement of life. In the past, the focus of an electric power company has been on the supply aspect of a management strategy, such as the stable provision of electric power through the construction of power equipment and least Cost planning. There has been a change of method in energy management. The balance of it seems to put forward to Demand Side Management(DSM) from Supply Side Management(SSM). Therefore, this paper is made a study for the method of energy grade of building.

• Journal of the Korea Society for Simulation
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• v.18 no.3
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• pp.47-59
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• 2009

Due to the application-specific nature of wireless sensor networks, the sensitivity to such a requirement as data reporting latency may vary depending on the type of applications, thus requiring application-specific algorithm and protocol design paradigms which help us to maximize energy conservation and thus the network lifetime. In this paper, we propose a novel delay-adaptive sensor scheduling scheme for energy-saving data gathering which is based on a two phase clustering (TPC). The ultimate goal is to extend the network lifetime by providing sensors with high adaptability to the application-dependent and time-varying delay requirements. The TPC requests sensors to construct two types of links: direct and relay links. The direct links are used for control and forwarding time critical sensed data. On the other hand, the relay links are used only for data forwarding based on the user delay constraints, thus allowing the sensors to opportunistically use the most energy-saving links and forming a multi-hop path. Simulation results demonstrate that cluster-based delay-adaptive data gathering strategy (CD-DGS) saves a significant amount of energy for dense sensor networks by adapting to the user delay constraints.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.4
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• pp.51-59
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• 2023

Despite countries' efforts to reduce carbon emissions, carbon emissions have increased in recent decades along with energy use, of which building energy uses account for a large proportion. Energy savings are essential as a strategy to reduce carbon emissions in existing buildings. The field experiment on the roof of a building located in Seoul was designed to measure the temperature reduction effect of green roof with rainwater storage tank to reduce cooling energy consumption in summer. The results showed that the mean mean surface temperature under the green roof was 14.77 degrees lower than that of the non-green roof from 13:00 P.M. to 15:00 P.M., which would have a great effect on reducing cooling energy. From 01:00 A.M. to 03:00 A.M., the effect was 3.36 degrees, showing that tropical nights could be improved. The temperature reduction effect due to the rainwater storage system increased by 1.45 degrees during the day and decreased by 0.63 degrees at night. The storage system can be strategically utilized to reduce carbon emissions during the week when cooling energy increases significantly.