• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.91-98
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• 2014

For the purpose of designing and applying the optimum surge protection scheme, multi-stage coordinated surge protective device(SPD) system is suitable to successfully fulfill its tasks; first, to divert a large amount of the transient energy, second, to clamp the overvoltage to the level below the withstand impulse voltage of the equipment to be protected. The length of SPD connecting leads shall be as short as possible. Long connecting leads will degrade the protection effect of SPDs. In this paper, the influences of the length of connecting leads on the energy sharing in a coordinated SPD system were investigated experimentally, and the simulation of determining the energy sharing and protection voltage level of each SPD depending on the length of connecting leads was carried out by using P-spice program. It was confirmed that the protection voltage level and energy sharing in coordinated SPD systems are strongly influenced by the length of connecting leads.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1152-1162
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• 2016

The unequal impedances of the interconnecting cables between paralleled inverters in the island mode of microgrids cause inaccurate reactive power sharing when the traditional droop control is used. Many studies in the literature adopt low speed communications between the inverters and the central control unit to overcome this problem. However, the losses of this communication link can be very detrimental to the performance of the controller. This paper proposes an improved reactive power-sharing control method. It employs infrequent measurements of the voltage at the point of common coupling (PCC) to estimate the output impedance between the inverters and the PCC and then readjust the voltage droop controller gains accordingly. The controller then reverts to being a traditional droop controller using the newly calculated gains. This increases the immunity of the controller against any losses in the communication links between the central control unit and the inverters. The capability of the proposed control method has been demonstrated by simulation and experimental results using a laboratory scale microgrid.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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• pp.341-348
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• 2021

The aim of this study is to fill gaps in emerging empirical evidence and negative electronic word of mouth (NeWOM) in repurchase intention (RI) moderated by the roles of social network sites (SNS) and company mitigation response (CMR). This type of research is descriptive. The sample used in this study is online consumers who buy energy drinks, based on the questionnaire obtained by 145 respondents. Based on the results of testing the estimation of the structural equation model, it was found that the negative variable brand experience sharing had no significant effect on NeWOM; the negative variable electronic reviews had a significant effect on the electronic word of mouth variable, the negative variable electronic reviews had a significant effect on the negative electronic variable word of mouth, the variable intensity of the use of social networking sites can strengthen the direction of the causal influence between the negative variables sharing brand experiences on negative electronic words of mouth. The variable social networking sites usage intensity can strengthen the direction of the effect of causality between negative electronic review variables on negative electronic word of mouth, the negative brand experience sharing variable does not have a significant effect on the repurchase intention variable.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.29-35
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• 2013

For the purpose of designing and applying optimum surge protection, one of the essential points is to take into account the energy coordination between cascaded surge protective devices(SPDs) and it is important to obtain an acceptable sharing of the energy stress between two cascaded SPDs. In this paper, in case of two voltage-limiting SPDs connected in parallel, the amount of splitting impulse current and energy that flow through each SPDs is investigated as a function of the protective distance. As a result, the energetic coordination between cascaded SPDs is strongly dependent on the voltage protection level of SPDs and the protective distance. It was confirmed that the sharing of the energy between two cascaded SPDs and the limited voltage levels are appropriate when the voltage protection levels of both upstream and downstream SPDs are the same.

• New & Renewable Energy
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• v.17 no.4
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• pp.9-27
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• 2021

Floating solar power markets are rapidly growing worldwide. The main policy instrument utilized to expand renewable energy use in foreign countries with many floating solar power installations is Feed-in-Tariffs (FITs). Foreign countries apply FIT to projects that have a secured grid connection, and lately, there has been a change in the direction of introducing or expanding auction systems. Vietnam and Taiwan give higher FIT to floating solar installations than land solar ones, and China, Vietnam, and Taiwan have higher FITs for certain regions. Compared to foreign countries where large-scale floating solar power installations have been installed, Korea has utilized Renewable Energy Certificate (REC) weights for residents' participation are provided additionally under the Renewable Portfolio Standard (RPS). In contrast to Korea, where residents' participation and benefit profit sharing are emphasized, the Netherlands provides opportunities for local residents to participate in floating solar power projects through cooperatives to improve the residents' acceptance.

• Journal of KIISE
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• v.42 no.11
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• pp.1430-1440
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• 2015

In contrast with battery-based wireless sensor networks (WSNs), solar-powered WSNs can operate for a longtime assuming that there is no hardware fault. Meanwhile, a mobile sink can save the energy consumption of WSN, but its ineffective movement may incur so much energy waste of not only itself but also an entire network. To solve this problem, many approaches, in which a mobile sink visits only on clustering-head nodes, have been proposed. But, the clustering scheme also has its own problems such as energy imbalance and data instability. In this study, therefore, a cluster-based energy-aware data-sharing scheme (CE-DSS) is proposed to effectively support a mobile sink in a solar-powered WSN. By utilizing the redundant energy efficiently, CE-DSS shares the gathered data among cluster-heads, while minimizing the unexpected black-out time. The simulation results show that CE-DSS increases the data reliability as well as conserves the energy of the mobile sink.

• New & Renewable Energy
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• v.17 no.2
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• pp.9-23
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• 2021

In Korea, various community investment renewable project models are being implemented to increase community acceptance of renewable energy. An important factor for enhancing local acceptance is that renewable energy projects have a positive effect on revitalizing the local economy such as income increase or job creation for residents and local companies. To maximize the local economic effect of large-scale community investment renewable energy projects, this study developed an evaluation index for local economy activation, whose indicators are the local return on investment, local companies' participation, local job creation, regional cooperation, transparency, and governance. Analysis of existing evaluation indicators and current renewable projects, financial analysis, and expert interviews were used in this research. The pilot evaluation determined that, the local economic effect was high in the following order: a fund investment wind project (Gangwon), benefit-sharing wind project (Jeju), and general wind project. In particular, residents' investment amount, the number of participating residents, and the amount and transparency of the regional cooperation fund were key factors to expand the effect of local economy activation. This evaluation index could be used in public bidding for renewable energy projects such as offshore wind zoning areas of local government.

• Korea Journal of Geothermal Energy
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• v.8 no.3
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• pp.44-54
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• 2012

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2569-2574
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• 2010

In this paper, we introduce an efficient energy management using a notion of virtual energy system for shared solar-powered sensor network. Virtual energy system is an abstraction that allows sensor network applications on a node to reserve their own fractions of the shared solar cell and the shared rechargeable battery, hence achieving logically partition of a shared renewable power source. Our results show that our design and implementation are reliable, lightweight and efficient, allowing proper isolation of energy consumption among applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.433-440
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• 2016

This paper proposes a method of minimizing total energy consumption of IoT environment when communication devices in the network share the information directly. The proposed method reduces total number of transmission for the information sharing by using an effective network coding-based technique which dynamically selects a node and a data packet for each transmission. Simulation results show that the proposed method has better performance than an existing network coding-based method selecting transmission node in fixed order, a network coding-based method selecting transmission node in random order, and a uncoded method selecting transmission node in random order.