• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.593-602
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• 2020

Recently, as research on smart farms has been actively conducted, systems for efficiently cultivating crops have been introduced and various energy systems using renewable energy such as solar, geothermal and wind power generation have been proposed to save the energy. In this paper, we propose a new and renewable energy convergence system for crops that provides energy independence and improved crop cultivation environment. First, we present LPWA-based communication node and gateway for ICT-based data collection. Then we propose an integrated monitoring server that collects energy data, crop growth data, and environmental data through a communication node and builds it as big data to perform optimal energy management that reflects the characteristics of the environment for cultivating crops. The proposed system is expected to contribute to the production of low-cost, high-quality crops through the fusion of renewable energy and smart farms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2971-2978
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• 2013

Recently, with the world-wide issues about global warming and CO2 reduction, a number of distributed generations(DGs) such as photovoltaic(PV) and wind power(WP), are interconnected with the distribution systems. However, DGs can change the direction of the power flow from one-direction to bi-direction, and also change the direction and amount of fault current of existing distribution systems. Therefore, it may cause the critical problems on the power quality and protection coordination. This paper proposes an operation algorithm for bi-directional protection coordination using and apply it for the evaluation system for protection coordination. From the simulation results It is found that the proposed method is more effective and convenient than existing method.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.65-75
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• 2018

The wind energy produced at night is being discarded because of the excess power generated at night compared to daytime. To solve this problem, In this study, we analyzed the evaluation contents for evaluation of domestic and overseas water electrolysis systems and drew contents for safety performance contents test of the water electrolysis system based on the evaluation contents. The test contents produced the efficiency measurement test, the hydrogen generated pressure test, and the hydrogen purity test. And the safety performance evaluation of the alkaline water electrolysis system of $5Nm^3/hr$ was performed based on the results. As a result, the hydrogen generation was calculated as $5.10Nm^3/hr$ and the stack efficiency was $4.97kWh/Nm^3$. The purity of the hydrogen generated was 99.993% and it was confirmed that it produced high purity hydrogen. I think will help us assess and build safety performance of water electrolysis systems in the future.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.3-17
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• 2004

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science research tools today and the potential field and micro-wave radar applications have been leading the discipline. The traditional optical imaging systems including the well known Landsat, NOAA - AVHRR, SPOT, and IKONOS have steadily improved spatial imaging resolution but increasing cloud covers have the major deterrent. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 - 2005 period and ALOS stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for launching in 2005) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. These new types of polarimetric imaging radars with repeat orbit interferometric capabilities are opening up completely new possibilities in Earth system science research, in addition to the radar altimeter and scatterometer. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of space-borne SAR systems is the future research tool for Earth observation and global environmental change monitoring. The potential field strength decreases as a function of the inverse square of the distance between the source and the observation point and geophysicists have traditionally been reluctant to make the potential field observation from any space-borne platforms. However, there have recently been a number of potential field missions such as ASTRID-2, Orsted, CHAMP, GRACE, GOCE. Of course these satellite sensors are most effective for low spatial resolution applications. For similar objects, AMPERE and NPOESS are being planned by the United States and France. The Earth science disciplines which utilize space-borne platforms most are the astronomy and atmospheric science. However in this talk we will focus our discussion on the solid Earth and physical oceanographic applications. The geodynamic applications actively being investigated from various space-borne platforms geological mapping, earthquake and volcano .elated tectonic deformation, generation of p.ecise digital elevation model (DEM), development of multi-temporal differential cross-track SAR interferometry, sea surface wind measurement, tidal flat geomorphology, sea surface wave dynamics, internal waves and high latitude cryogenics including sea ice problems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1675-1681
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• 2017

As recently the demand on electric power has been increasing, the requirement of power supply reliability has been increased. Accordingly, the number of HVDC transmission systems in the world has been steadily increased, which have been installed in the power system to transmit a large capacity power to the long distant and interconnect the power grid between different countries. etc. #1 HVDC Transmission System was installed between Haenam and Jeju island in 1998, which is the first HVDC system furnished in korea. and has been operated until now. Before #1 HVDC Transmission System being installed, the power system of the Jeju Island is a isolated power system from that of Korea mainland. After the construction of #1 HVDC the system has made the Jeju power system more reliable and also been able to supply the mainland power, which was cheaper than that of Jeju island, to Jeju island. The construction of additional HVDC transmission system between mainland and the Jeju Island has been currently underway to cope with recent changes of the power market of the Jeju island, for examples the increase of power demand and the capacity of wind power generation. etc. #2 HVDC Transmission System construction was completed in 2012. #3 HVDC Transmission System will be also installed according to the plan. If all goes as planned, the Jeju power system will be operated with Multi-Infeed HVDC system connected to mainland power system. So the additional studies are needed in order to maintain the stability of the Jeju power system and get the efficiency of the Multi-Infeed HVDC system. Therefore, in this paper, the optimal operation strategies of the Multi-Infeed HVDC system between the mainland of Korea and the Jeju are suggested to ensure the stability of the power system in Jeju Island when the Multi-Infeed HVDC system is operated between two power system.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.125-132
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• 2011

A unitized regenerative fuel cell (URFC) as a next-generation fuel cell technology was considered in the study. URFC is a mandatory technology for the completion of the hybrid system with the fuel cell and the renewable energy sources, and it can be expected as a new technology for the realization of hydrogen economy society in the $21^{st}$ century. Specifically, the recent research data and results concerning the polymer electrolyte membrane for the URFC technology were summarized in the study. The prime requirements of polymer electrolyte membrane for the URFC applications are high proton conductivity, dimensional stability, mechanical strength, and interfacial stability with the electrode binder. Based on the performance of the polymer electrolyte membrane, the URFC technology combining the systems for the production, storage, utilization of hydrogen can be a new research area in the development of an advanced technology concerning with renewable energy such as fuel cell, solar cell, and wind power.

• 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 the Korea Society for Simulation
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• v.30 no.2
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• pp.1-9
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• 2021

Many factors such as wind direction, wind strength, temperature, and obstacles affect a munition's trajectory. Since these factors eventually determines the probability of hit and the hitting point of a target, these factors should be considered to obtain reliable weapon effectiveness data. In this study, we propose the extension of the MSDL(Military Scenario Definition Language) to reflect these factors to improve the reliability of weapon effectiveness data. Based on the existing MSDL, which has been used to set the initial condition of a military simulation scenarios, the newly identified subelements are added in ScenarioID, Environment, Organizations, and Installations as a scenario schema. Also, DamageAssessment and DesignOfExperiments element are added to make weapon effectiveness data easily. The extended MSDL enables to automatically generate the simulation scenarios that reflect various factors which affect the probability of hit or kill. This extended MSDL is applied to an integrated simulation software of weapon systems, named AddSIM version 4.0 for generation of weapon effectiveness data.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.71-78
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• 2020

In the case of power generation using renewable energy, power production may not be smooth due to the influence of the weather. The energy storage system (ESS) is used to increase the efficiency of solar and wind power generation. ESS has been continuously fired due to a lack of battery protection systems, operation management, and control system, or careless installation, leading to very big casualties and economic losses. ESS stability and battery protection system operation management technology is indispensable. In this paper, we present a battery level calculation algorithm and a failure prediction algorithm for ESS optimization and stable operation. The proposed algorithm calculates the correct battery level by accumulating the current amount in real-time when the battery is charged and discharged, and calculates the battery failure by using the voltage imbalance between battery cells. The proposed algorithms can predict the exact battery level and failure required to operate the ESS optimally. Therefore, accurate status information on ESS battery can be measured and reliably monitored to prevent large accidents.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.95-102
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• 2022

It is a study for the evaluation of the stability of the distribution automation system for the expansion of renewable energy. Through the Renewable Energy 3020 Implementation Plan, the government plans to expand new renewable energy and convert it to participatory energy that improves the quality of life of the people by 2030. The government has set a target of 20% of domestic supply energy for renewable energy generation by 2030. It is planning to establish more than 95 percent of its new facilities with clean energy such as solar power and wind power. By expanding the supply of renewable energy, new energy businesses and distributed power industry were fostered, and short-distance, low-voltage, and small-scale power generation were rapidly expanded rather than large-scale power development in the past. Due to this demand, the importance of power distribution facility operation has emerged and the need for distribution automation system is increasing. This paper discusses the development of a power distribution simulator for the performance and function evaluation of power distribution automation systems and presents the results of an interlocking test with the power distribution automation system. In order to introduce an advanced system into the power distribution system, it is necessary to take advantage of the transmission and distribution system. The DNP3.0 protocol is used in the distribution system and the IEC61850 protocol is used in the transmission and distribution system. It was concluded that the functions and performance of operations were satisfied when these two protocols are mixed and used in the distribution automation system.