• Proceedings of the KIPE Conference
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• 2004.11a
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• pp.124-126
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• 2004

This paper describes a boost converter cascaded high frequency link direct do-ac converter suitable for fuel cell power sources. A new multi-loop control for a boost converter to reduce the low frequency input current harmonics drawn from fuel cell is proposed. A new PWM technique for the cycloconverter at the secondary to reject the low order harmonics in the output voltages is presented in detail.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.245-249
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• 2005

This paper describes a boost converter cascaded high frequency link direct dc-ac converter suitable for fuel cell power sources. A new multi-loop control for a boost converter to reduce the low frequency input current harmonics drawn from fuel cell is proposed. A new PWM technique for the cycloconverter at the secondary to reject the low order harmonics in the output voltages is presented in detail.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.580-588
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• 2016

Energy efficiency is the main objective in the design of a wireless sensor network (WSN). In many applications, sensing data must be transmitted from sources to a sink in a timely manner. This paper describes an investigation of the trade-off between two objectives in WSN design: minimizing energy consumption and minimizing end-to-end delay. We first propose a new distributed clustering approach to determining the best clusterhead for each cluster by considering both energy consumption and end-to-end delay requirements. Next, we propose a new energy-cost function and a new end-to-end delay function for use in an inter-cluster routing algorithm. We present a multi-hop routing algorithm for use in disseminating sensing data from clusterheads to a sink at the minimum energy cost subject to an end-to-end delay constraint. The results of a simulation are consistent with our theoretical analysis results and show that our proposed performs much better than similar protocols in terms of energy consumption and end-to-end delay.

• Advances in Energy Research
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• v.5 no.4
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• pp.321-339
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• 2017

Energy simulation tools can provide information on the amount of heat transfer through building envelope components, which are considered the main sources of heat loss in buildings. Therefore, it is important to improve the quality of outputs from energy simulation tools and also the process of obtaining them. In this paper, a new Building Energy Performance Assessment Tool (BEPAT) is introduced, which provides users with granular data related to heat transfer through every single wall, window, door, roof, and floor in a building and automatically saves all the related data in text files. This information can be used to identify the envelope components for thermal improvement through energy retrofit or during the design phase. The generated data can also be adopted in the design of energy smart homes, building design tools, and energy retrofit tools as a supplementary dataset. BEPAT is developed by modifying EnergyPlus source code as the energy simulation engine using C++, which only requires Input Data File (IDF) and weather file to perform the energy simulation and automatically provide detailed output. To validate the BEPAT results, a computer model is developed in Revit for use in BEPAT. Validating BEPAT's output with EnergyPlus "advanced output" shows a difference of less than 2% and thus establishing the capability of this tool to facilitate the provision of detailed output on the quantity of heat transfer through walls, fenestrations, roofs, and floors.

• New & Renewable Energy
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• v.18 no.2
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• pp.18-25
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• 2022

In this study, we propose a wind power generation prediction system that applies machine learning and data mining to predict wind power generation. This system increases the utilization rate of new and renewable energy sources. For time-series data, the data set was established by measuring wind speed, wind generation, and environmental factors influencing the wind speed. The data set was pre-processed so that it could be applied appropriately to the model. The prediction system applied the CNN (Convolutional Neural Network) to the data mining process and then used the LSTM (Long Short-Term Memory) to learn and make predictions. The preciseness of the proposed system is verified by comparing the prediction data with the actual data, according to the presence or absence of data mining in the model of the prediction system.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.32.3-32.3
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• 2016

Available VLBI sources at high frequencies (e.g. >22GHz) are very limited - mainly due to atmospheric fluctuations that degrade coherence time and a power-law energy distribution of particles in case of AGNs. However, simultaneous multi-frequency VLBI receiving system of the Korean VLBI Network (KVN) and its powerful VLBI phase calibration technique offer benefits in finding more weak sources at millimeter wavelengths. Based on this aspect, multi-frequency AGN survey with the KVN (MASK) project, which aims to densify an existing a VLBI catalog of extragalactic radio sources at 22/43/86/129GHz is proposed as a KVN legacy program. We selected 1220 sources of AGNs that include known VLBI sources and new fringe-detected sources using the KVN at K-band (22GHz). Among them, 138 sources were observed as pilot experiments at 22/43/86/129GHz simultaneously and excellent VLBI detection results are achieved. Therefore, we expect that MASK will open a new era in VLBI science at millimeter wavelengths by providing unprecedented number of available sources in the Universe.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.168-171
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• 2006

After an incandescent lamp developed as a first light source using electric energy in 1879, various lamps have been developed and promoted for usual convenience. Although lots of light sources have been developed for the past centry, among them some were used widely but some were hardly used contray to the initial expectations. Incandescent, fluorescent, HID and LED lamps which are normally used these days were treated as new type of light sources and very difficult to be popularized at the initial stage. In spite of the initial difficulties, these light sources and luminaries are still so popular because all of them were improved to be used easily by reflecting human's mental and physiological state. Like this when new light sources and luminaries are developed, a careful consideration, if these are proper for the surroundings or not, must be preceded. This study finally derived development factors of PLS developed in domestic to be played an important role in future light by analyzing product trends, social and lighting development changes.

• New & Renewable Energy
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• v.1 no.3 s.3
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• pp.24-34
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• 2005

Ministry of Commerce, Industry [MOCIE] has taken it into consideration to introduce a Renewable Portfolio Standard (RPS) that is a purchase obligation program as an alternative plan to the FIT. We conducted a survey of renewable energy companies and experts to ask their opinions about renewable energy policy, the introduction of the RPS, and the scheme for aid of North Korea with renewable energy. Korean renewable energy companies show an impartial opinion about a FIT and a RPS system overall, although they tend to have distinctive opinions by technology each other. With respect to eligible resources for a RPS, the industries want to extend the scope of it as broad as possible. In addition, experts prefer the multi-tiered and energy production based RPS to the sing1e-tiered and installed capacity based RPS. We also conducted a surrey to find the best renewable energy sources. Wind, Geothermal, Solar-thermal, and Photovoltaic were selected to have the best potential capacities to support North Korea by renewable energy experts. However, these energy resources also have several problems to overcome in the aid of North Korea, and thus, the plans for solving them and for giving efficient support to North Korea in the area of Renewable Energy are discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.123-126
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• 2005

Recently, because of the depletion of fossil fuels and the environmental pollution by using fossil fuels and harmfulness of atomic power plants. the interests concerning new and renewable energy resources are rising increasingly. And of all new and renewable energy sources the PV generation systems are recognized as the most useful and desirable renewable energy source in allowance for installation conditions. In this development, the 3kWp photovoltaic power generation system is realized to verify the performance of the 3kWp PCS developed by Hyundai Heavy Industries Co. (HHI). The photovoltaic array used in this system is composed of 60 modules of 50Wp capacity. The developed system is tested as procedures and items of test regulation recognized by governmen and the experimental results show the excellent electrical characteristics. Now, the 3kWp PCS developed is installed in the PV model house built in HHI plant and is being tested for practical use commercialization.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.136.1-136.1
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• 2011

An energy modeling analysis method currently has been considered as a new approach for energy policy research, because the importance of renewable energy use has been emphasized more and more. This study used RETScreen model as a clean energy decision making methodology for adaptation to climate change and elimination of various pollutions. This modeling method includes five step standard analysis; energy model, cost analysis, GHG analysis, financial analysis, and sensitivity & risk analysis and it also assesses both conventional and modern energy sources and technologies. This methodology for the photovoltaic(PV) energy modeling is used to evaluate the energy production, financial performance and GHG emissions reduction of photovoltaic projects. In addition, the PV application systems are classified into three basic applications; On-grid system, Off-grid system and water pumping system. This study assesses the renewable energy techno-economic modeling method with the feasibility analysis result of 10 MW PV power plant in Abu Dhabi in United Arab Emirates. Furthermore this study stresses the importance of renewable energy model research by applying to domestic PV power plant which is now in preparation.