• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.129-139
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• 2010

This paper presents a basic energy performance data of microturbine, renewable Energy(BIPV and Solar Collector System) and a hybrid energy system(geothermal system and microturbine) installed in hospital building. The efficiency of solar collector and BIPV system was 30[%], 10[%] individually, and lower than micro turbines. Finally, in energy performance aspect, microturbine and geothermal source heat pump system were a high-efficiency system in hospital building. It is confirmed hybrid energy systems also show the most powerful alternative energy system for green hospital building from the simulation results.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.15-24
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• 2011

Modeling and simulation for Green Energy depends largely on the type of system under investigation. The topics are very wide ranging from semiconductor physics (solar), electrical motor/generator (wind turbines), power electronics (grid connections) to typical control strategies. To correctly model these technologies requires a broad set of models and various simulation techniques. To further refine or detail the simulation the modeling has to be performed on a specific level, being system, circuit or component level. Combinations of several levels allows gradually improving the validity of the overall model against available parameters and model equations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5712-5728
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• 2017

Recently, there are many studies, that considering green wireless cellular networks, have taken the energy consumption of the base station (BS) into consideration. In this work, we first introduce an energy consumption model of multi-mode sharing BS powered by multiple energy sources including renewable energy, local storage and power grid. Then communication load requests of the BS are transformed to energy demand queues, and battery energy level and worst-case delay constraints are considered into the virtual queue to ensure the network QoS when our objective is to minimize the long term electricity cost of BSs. Lyapunov optimization method is applied to work out the optimization objective without knowing the future information of the communication load, real-time electricity market price and renewable energy availability. Finally, linear programming is used, and the corresponding energy efficient scheduling policy is obtained. The performance analysis of our proposed online algorithm based on real-world traces demonstrates that it can greatly reduce one day's electricity cost of individual BS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.526-534
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• 2009

The magnetic field of the extremely low frequency that occurs in the substation facilities was surveyed to present ways to broaden understanding of the magnetic field characteristics. We have investigated the level of the magnetic fields in the substation areas and control rooms of 25 substations in the metropolitan area in accordance with the measurement method of IEC CISPR(IEC/TC106 PT 62110). We propose objective and reliable policy approaches such as the electromagnetic field certification system to more accurately understand the property of magnetic field.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.103-114
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• 2017

The landslide disaster damage has been increased by mountain development, leading to construction of educational facilities, medical facilities, petty industrial facilities, and large housing complexes. Therefore, effective regulation is required as an effort in urban planning solutions. For suggesting specific mitigation strategies on urban landslide, this study aims to define evaluation criteria for urban planning management of debris-flow disaster. AHP (Analytic Hierarchy Process), one of the multiple criterion decision making methods, was utilized in this study. This study makes use of 16 sub-criteria under the framework of hazard, exposure, and vulnerability, and well-planned expert survey measures their weights. The weights are also applied to evaluate each grid in urban space (min $10{\times}10m$) and classify it with red, orange, yellow, or green grade so that areas at higher risk are clearly identified. This study concludes that the suggested method is useful to support a strategies for urban planning management of debris-flow disaster, particularly in a GIS base.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.72-79
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• 2011

Typical results obtained by a newly developed, nonlinear time domain hybrid method for simulating large amplitude motions of ships advancing with constant forward speed in waves are presented. The method is hybrid in the way of combining a time-domain transient Green function method and a Rankine source method. The present approach employs a simple double integration algorithm with respect to time to simulate the free-surface boundary condition. During the simulation, the diffraction and radiation forces are computed by pressure integration over the mean wetted surface, whereas the incident wave and hydrostatic restoring forces/moments are calculated on the instantaneously wetted surface of the hull. Typical numerical results of application of the method to the seakeeping performance of a standard containership, namely the ITTC S175, are herein presented. Comparisons have been made between the results from the present method, the frequency domain 3D panel method (NEWDRIFT) of NTUA-SDL and available experimental data and good agreement has been observed for all studied cases between the results of the present method and comparable other data.

• The Korean Journal of Ecology
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• v.28 no.1
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• pp.1-6
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• 2005

This study was conducted to develop the predictive model for species richness of breeding birds by multivariate analysis of land covers (percentage value of each cover in 300 $\times$ 300m grid) including water area (WA), urbanized area (UA), green area (GA), forest area (FA) and agricultural area (AA) at Seongnam City in Korea. Fifty-nine species of birds were mapped on 155 grids in size of 300 $\times$ 300 m from 2000 to 2001. Species richness of breeding birds was significantly regressed ($R^2=0.85$, n=155) by estimates of WA ($4.59{\pm}1.13$, P<0.0001), UA ($6.50{\pm}0.86$, P<0.0001), GA ($7.11{\pm}1.25$, P<0.0001), FA ($8.51{\pm}0.62$, P<0.0001), and AA ($4.59{\pm}1.13$, P<0.0001). In validation of model, the results show no significant difference between predicted value of species richness and observed one. Developed model can be used as a predictive model of species richness of birds for selecting the proper location of corridors and parks in urban area.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1874-1885
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• 2018

The customer side operation is getting more complex in a smart grid environment because of the adoption of renewable resources. In performing energy management planning or scheduling, it is essential to forecast non-controllable resources accurately and robustly. The PV system is one of the common renewable energy resources in customer side. Its output depends on weather and physical characteristics of the PV system. Thus, weather information is essential to predict the amount of PV system output. However, weather forecast usually does not include enough solar irradiation information. In this study, a PV system power output prediction model (PPM) under limited weather information is proposed. In the proposed model, meteorological radiation model (MRM) is used to improve cloud cover radiation model (CRM) to consider the seasonal effect of the target region. The results of the proposed model are compared to the result of the conventional CRM prediction method on the PV generation obtained from a field test site. With the PPM, root mean square error (RMSE), and mean absolute error (MAE) are improved by 23.43% and 33.76%, respectively, compared to CRM for all days; while in clear days, they are improved by 53.36% and 62.90%, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.136-142
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• 2010

In this paper, we changed $SF_6$ insulation gases used already in the GIB(Gas Insulated Bus, gas insulated busbar) of switching appliances of power grid 170[kV] GIS(Gas Insulated Switchgear, Gas Insulated Switchgear) with green insulation dry air gases and studied dielectric breakdown voltage characteristics by the AC voltage withstand test. Withstand test AC voltage applied to the standard KEPCO's 170[kV] GIB with dry air insulation and and the equivalent of dry air and $SF_6$ gas were examined. Breakdown voltage of dry air, using an expression of the experiments were calculated and AC Withstand criterion of dry air insulation for the AC voltage test was derived. Using the criterion, dry air gases can be used instead of the $SF_6$ gas was confirmed in the factory acceptance test at 170[kV] GIB.

• Ceramist
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• v.21 no.4
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• pp.312-330
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• 2018

Energy storage/conversion has become crucial not only to meet the present energy demand but also more importantly to sustain the modern society. Particularly, electrical energy storage is critical not only to support electronic, vehicular and load-levelling applications but also to efficiently commercialize renewable energy resources such as solar and wind. While Li-ion batteries are being intensely researched for electric vehicle applications, there is a pressing need to seek for new battery chemistries aimed at stationary storage systems. In this aspect, Zn-ion batteries offer a viable option to be utilized for high energy and power density applications since every intercalated Zn-ion yields a concurrent charge transfer of two electrons and thereby high theoretical capacities can be realized. Furthermore, the simplicity of fabrication under open-air conditions combined with the abundant and less toxic zinc element makes aqueous Zn-ion batteries one of the most economical, safe and green energy storage technologies with prospective use for stationary grid storage applications. Also, Zn-ion batteries are very safe for next-generation technologies based on flexible, roll-up, wearable implantable devices the portable electronics market. Following this advantages, a wide range of approaches and materials, namely, cathodes, anodes and electrolytes have been investigated for Zn-ion batteries applications to date. Herein, we review the progresses and major advancements related to aqueous. Zn-ion batteries, facilitating energy storage/conversion via $Zn^{2+}$ (de)intercalation mechanism.