• Journal of the Korea Institute of Building Construction
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• v.11 no.2
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• pp.116-126
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• 2011

Recently, eco-friendly energy has been employed in diverse fields of industry in order to reduce environmental pollution and secure a new growth engine. In particular, practical applications of photovoltaic energy, such as building integrated photovoltaic systems, have been implemented to the construction industry based on the extensive interest in photovoltaic power as an unlimited and sustainable energy. While the construction of a high-rise building requires large amounts of energy, methods of reducing energy consumption in the construction phase have rarely been studied. Based on this motivation, the research proposes a photovoltaic based formwork system (PVFS), and then performs a design and feasibility analysis for its application to the construction of a high-rise building. Using a case study, the research implements various analyses, including area, position, and total allowable weight required by PVFS, and evaluates the influences of PVFS on the construction processes, as well as its economic feasibility. The proposed PVFS can be adopted to a real-world project in the near future, depending on the advancement of technology and economic feasibility. The results of this research will contribute to establishing a construction environment that promotes a reduction of energy consumption by using eco-friendly energy in the construction phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.568-574
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• 2020

Recently, the installation of energy storage systems (ESSs) that have a range of functions, such as power stabilization of renewable energy sources, demand control, and frequency regulation, has been increasing annually. On the other hand, since the fire accident of ESS occurred at Gochang Power Test Center in August 2017, 29 fire accidents with significant property losses have occurred, including the Gyeongsan substation and Kunsan PV power plant. Because these fire accidents of ESS are arisen regardless of the season and capacity of ESS, an analysis of the fault characteristics in ESS is required to confirm the causes of the fire accidents accurately and ensure the safety of the ESS. This paper proposes the modeling of ESS using PSCAD/EMTDC S/W to identify the fault characteristics and ensure the safety of the ESS. From the simulation results of fault characteristics based on various scenarios, it is clear that the insulation of ESS may be breakdown due to the largely occurring CMV (common mode voltage). Furthermore, the CMV between the PCS and battery can be reduced, and the insulation breakdown of ESS can be prevented if an SPD (surge protect device) is installed in the battery and PCS sides, respectively.

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.47-56
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• 2011

Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.479-494
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• 2017

After Fukushima incident, negative sentiment towards nuclear power has led to transition in policies that reduce the dependency on nuclear power in some countries. President Moon of Republic of Korea also announced a national plan of decommissioning retired nuclear power plants stage by stage. Therefore, nuclear power that once was considered the critical solution to energy security and climate change is now a limited option. This study aims to find an optimal energy mix in Korea's electricity system from 2016 through 2030 to combat climate change through energy transition with minimum cost. The study is divided into two different scenarios; energy transition and nuclear sustenance, to compare the total costs of the systems. Both scenarios show that electricity generated by wind technology increases from 2018 whereas that of photovoltaic(PV) increases from 2021. However, the total cost of the energy transition scenario was USD 4.7 billion more expensive than the nuclear sustenance scenario.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.199-212
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• 2010

To establish an infrastructure for technology and information in the domestic construction industry, several construction regulations pertaining to construction information have been institutionalized. However, there are major problems with the domestic information classification system, earned value management (EVM) and project management information system (PMIS). In particular, the functions of the current PMIS have consisted of a builder-oriented system, and as EVM is not applied to PMIS, the functions of reporting, analysis and forecast for owners are lacking. Moreover, owners cannot confirm information on construction schedule and cost in real time due to the differences between the EVM and PMIS operation systems. The purpose of this study is to provide a framework that is capable of operating PMIS efficiently under an e-business environment, by providing a proposal on how to establish a work breakdown structure (WBS) and an EVM - PMIS integration model, so that PMIS may provide the function of EVM, and stakeholders may have all information in common. At the core of EVM - PMIS integration is the idea that EVM and PMIS have the same operation system, in order to be an activity-based system. The principle of the integration is data integration, in which the information field of an activity is connected with the field of a relational database table consisting of sub-modules for the schedule and cost management function of PMIS using a relational database management system. Therefore, the planned value (PV), cost value (CV), actual cost (AC), schedule variance (SV), schedule performance index (SPI), cost variance (CV) and cost performance index (CPI) of an activity are connected with the field of the relational database table for the schedule and cost sub-modules of PMIS.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.369-374
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• 2015

This study analyzed analyzes the energy performance of six houses in Daejeon completed which were built in 2011. Observed The observed houses, which were all designed and constructed inof the same size and structure, are were highly insulated with triple Low-E coating windows; the insulation level of the walls is was $0.13W/m^2K$ and that of the roof is was $0.10W/m^2K$. As electric houses, all of the energy supplied to the houses, including for cooking, is was supplied by electricity. A and 3~4 kWp of photovoltaic system and a 3~5 kW of ground source heat pump (GSHP) were installed in each house tofor providing provide space heating/and cooling and hot water are installed. We constructed a Web-based remote monitoring system in order to understand energy consumption and the dynamic behavior of the energy system. T, and the results of our metering data analysis of 2013 are as follows. First, the annual residential energy consumption is was 4,400 kWh (${\sigma}=1,209$) and GSHP energy consumption is was 5,182 kWh (${\sigma}=1,164$). Second, residential energy consumption ranked highest in average energy usage, with at 45% of the total, followed by heating with at 30%, hot water supply with at 17% and cooling with at 6%. Third, the average energy independence rate is was 51.8%, the GFA (Gross gross floor area) criteria average energy consumption unit is was $48.7kWh/m^2yr$ (${\sigma}=10.1$), and the net energy consumption unit (except the energy yield of the PV systems) is was $24.7kWh/m^2yr$ (${\sigma}=8.8$).

• Solar Energy
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• v.11 no.3
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• pp.3-8
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• 1991

There are fifteen solar radiation measurement stations over the entire country in Korea. However, they are not capable of supplying reliable solar radiation data for remote areas including islands. The un-manned automated insolation measurement station is suitable for these areas due to the electric power shortage and the maintenance problems at these isolated areas. Our main aim in this work is to develop a solar radiation measurement system which collects and stores data by itself utilizing a PV module and a battery as power source for entire system irregardless of the environmental condition. A developed KIER's prototype system along with an independent HWS reference system has been installed at the designated remote island, Dok-do. Global solar radiation has been measured every hour for a 6-month period of time by both systems at this site. A comparison between the measured solar radiation data by each system indicates that there is an excellent agreement showing average 3.0% of an absolute error. It has been observed that the 8-month average global solar radiation was $2,330W/m^2$ day at this island. We came to the conservative conclusion that the developed KIER system is applicable for measuring solar radiation and for supplying reliable fundamental design data for solar energy utilization system at the remote areas.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.273-281
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• 2019

The energy consumed by buildings among the total national energy consumption is more than 10% of the total. For this reason, Korea has adopted the zero energy building policy since 2025, and research on the energy saving technology of buildings has been demanded. Analysis of buildings' energy consumption patterns shows that lighting, heating and cooling energy account for more than 60% of total energy consumption, which is directly related to solar power acquisition and window opening and closing operation. In this paper, we have developed a low - power IoT sensor module for window system to transfer acquired information to building energy management system. This module transmits the external environment and window opening / closing status information to the building energy management system in real time, and constructs the network to actively take energy saving measures. The power used in the module is designed as an independent power source using solar power among the harvest energy. The topology of the power supply is a Buck converter, which is charged at 4V to the lithium ion battery through MPPT control, and the efficiency is about 85.87%. Communication is configured to be able to transmit in real time by applying WiFi. In order to reduce the power consumption of the module, we analyzed the hardware and software aspects and implemented a low power IoT sensor module.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.61-68
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• 2021

The application of renewable energies such as wind and solar has become an inevitable choice for many countries in order to achieve the reduction of greenhouse gases and healthy economic development. However, due to the intermittent characteristics of renewable energy, the issue with integrating a larger proportion of renewable energy into the grid becomes more prominent. A complex energy system, usually consists of two or more renewable energy sources used together to provide increased system efficiency as well as greater balance in energy supply. Compared with the power system, control and optimization of the complex energy system become more difficult in terms of modeling, operation, and planning. The main purpose of the complex energy system retrofit for samado island with microgrid system is to coordinate the operation with various distributed energy resources, energy storage systems, and power grids to ensure its reliability, while reducing the operating costs and achieving the optimal economic benefits. This paper suggests the improved complex energy system of samado island with optimal microgrid system. The results of test operation show about 12% lower SOC variation band of ESS, elimination of operation limit in PV and reduction of operation time in diesel generator.

• Information Systems Review
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• v.11 no.1
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• pp.161-179
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• 2009

Nowadays an increasing number of Internet users are running individual websites as Blog or Cyworld. As this type of personal media has a great influence on communication among people, business comes to care about Network Effect, Network Software, and Social Network. For instance, Cyworld created the web service called 'Minihompy' for individual web-logs, and acquired 2.4milion users in 2007. Although many people assumed that the popularity of Minihompy, or Blog would be a passing fad, Cyworld has improved its service, and expanded its Network with various contents. This kind of expansion reflects survival efforts from infinite competitions among ISPs (Internet Service Provider) with focus on enhancing usability to users. However, Cyworld's Network Effect is gradually diminished in these days. Both of low production cost of service vendors and the low searching/conversing costs of users combine to make ISPs hard to keep their market share sustainable. To overcome this lackluster trend, Cyworld has adopted new strategies and try to lock their users in their service. Various efforts to improve the continuance and expansion of Network effect remain unclear and uncertain. If we understand beforehand how a service would improve Network effect, and which service could bring more effect, ISPs can get substantial help in launching their new business strategy. Regardless many diverse ideas to increase their user's duration online ISPs cannot guarantee 'how the new service strategies will end up in profitability. Therefore, this research studies about Network effect of Cyworld's 'Minihompy' using System-Dynamics method which could analyze dynamic relation between users and ISPs. Furthermore, the research aims to predict changes of Network Effect based on the strategy of new service. 'Page View' and 'Duration Time' can be enhanced for the short tenn because they enhance the service functionality. However, these services cannot increase the Network in the long-run. Limitations of this research include that we predict the future merely based on the limited data. We also limit the independent variables over Network Effect only to the following two issues: Increasing the number of users and increasing the Service Functionality. Despite of some limitations, this study perhaps gives some insights to the policy makers or others facing the stiff competition in the network business.