• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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• pp.75-75
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• 2011

This paper has been studied that ocean wave vibration power generator is composed of buoy and vibration generator to make effective use of ocean wave energy. We designed buoy to can occur resonance for dominant frequency with ocean wave. And then we fitted the natural frequency of vibration system with vibration power generator to buoy's natural frequency. And we can show that the amplitude of ocean wave up and down motion is decreased, on the other hand, the displacement of vibration system with vibration power generator is increased. Therefore, ocean wave vibration power generator which is proposed in this paper has merits not only securing its stability from surroundings but also producing more electronic power by using ocean wave energy.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.721-733
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• 2020

In nuclear engineering, the occurrence of critical heat flux (CHF) is complicated for rod bundle, and it is much more difficult to predict the CHF when it is in natural circulation under motion condition. In this paper, the dryout-type CHF is investigated for the rod bundle in a natural circulation loop under rolling motion condition based on the coupled analysis of subchannel method, a one-dimensional system analysis method and a CHF mechanism model, namely the three-fluid model for annular flow. In order to consider the rolling effect of the natural circulation loop, the subchannel model is connected to the one-dimensional system code at the inlet and outlet of the rod bundle. The subchannel analysis provides the local thermal hydraulic parameters as input for the CHF mechanism model to calculate the occurrence of CHF. The rolling motion is modeled by additional motion forces in the momentum equation. First, the calculation methods of the natural circulation and CHF are validated by a published natural circulation experiment data and a CHF empirical correlation, respectively. Then, the CHF of the rod bundle in a natural circulation loop under both the stationary and rolling motion condition is predicted and analyzed. According to the calculation results, CHF under stationary condition is smaller than that under rolling motion condition. Besides, the CHF decreases with the increase of the rolling period and angular acceleration amplitude within the range of inlet subcooling and mass flux adopted in the current research. This paper can provide useful information for the prediction of CHF in natural circulation under motion condition, which is important for the nuclear reactor design improvement and safety analysis.

• Architectural research
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• v.21 no.1
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• pp.21-29
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• 2019

Recent years in Korea, some new developed buildings are only using electricity as power for heating, cooling, bathing and even cooking which means except electricity, there is no natural gas or other kinds of energy used in such kind of building. In vehicle industry area, scientists already invented electric vehicle as an environment friendly vehicle; after that, in architecture design and construction field, buildings only using electricity appeared; the curiosity of the environment impact of energy consumption by such kind of building lead me to do this research. In general, electricity is known as a clean energy resource reasoned by it is noncombustible energy resource; however, although there is no environmental pollution by using electricity, electricity generation procedure in power plant may cause huge amount of environment pollution; especially, electricity generation from combusting coal in power plant could emit enormous air pollutants to the air. In this research, the yearly amount of air pollution by energy using under traditional way in research target building that is using natural gas for heating, bathing and cooking and electricity for lighting, equipment and cooling is compared with yearly amount of air pollution by only using electricity as power in the building; result shows that building that only uses electricity emits much more air pollutants than uses electricity and natural gas together in the building. According to the amount of air pollutants comparison result between two different energy application types in the building, residential SOFC (Solid oxide fuel cell) is simulated to apply in this building for decreasing environment pollution of the building; furthermore, high load factor could lead high efficiency of SOFC, in the scenario of simulating applying SOFC in the building, SOFC is shared by two or three households in spring and autumn to increase efficiency of the SOFC. In sum, this research is trying to demonstrate electricity is a conditioned environment friendly energy resource; in the meanwhile, SOFC is simulated efficiently applying in the building only using electricity as power to decrease the large amount of air pollutants by energy using in the building. Energy consumption of the building is analyzed by calibrated commercial software Design Builder; the calibrated mathematical model of SOFC is referred from other researcher's study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.219-219
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• 2008

Energy harvesting from the environment has been of great interest as a standalone power source of wireless sensor nodes for ubiquitous sensor networks (USN). There are several power generating methods such as thermal gradients, solar cell, energy produced by human action, mechanical vibration energy, and so on. Most of all, mechanical vibration is easily accessible and has no limitation of weather and environment of outdoor or indoor. In particular, the piezoelectric energy harvesting from ambient vibration sources has attracted attention because it has a relative high power density comparing with other energy scavenging methods. Through recent advances in low power consumption RF transmitters and sensors, it is possible to adopt a micro-power energy harvesting system realized by MEMS technology for the system-on-chip. However, the MEMS energy harvesting system hassome drawbacks such as a high natural frequency over 300 Hz and a small power generation due to a small dimension. To overcome these limitations, we devised a novel power generator with a spiral spring structure. In this case, the energy harvester has a lower natural frequency under 200 Hz than a normal cantilever structure. Moreover, it has higher an energy conversion efficient because shear mode ($d_{15}$) is much larger than 33 mode ($d_{33}$) and the energy conversion efficiency is proportional to the piezoelectric constant (d). We expect the spiral type MEMS power generator would be a good candidate as a standalone power generator for USN.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.318-323
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• 2024

In this paper, computer modeling works have been performed for the power generation Rankine cycle using new working fluids and liquefied natural gas (LNG) cold heat. PRO/II with PROVISION released January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the power generation cycle. Optimal working fluid composition was determined to maximize LNG cold heat to increase power generation efficiency and net power production.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.170-177
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• 2020

Stoichiometric combustion in spark ignition (SI) engines has an advantage of meeting future stringent emission regulations. However, the drawback of the combustion is a lower thermal efficiency than that of lean burn. In this study, energy losses in a natural gas stoichiometric SI engine generator were analyzed to establish a strategy for improving the generating efficiency (GE). The energy losses were investigated based on dynamometer and load bank experiments. As the intake manifold pressure increased in the dynamometer experiment, the brake thermal efficiency (BTE) increased mainly due to the reduction in the pumping and mechanical losses. In the load bank experiment, the generating power and GE increased with the increased intake manifold pressure. The generating power and GE were lower than the brake power and BTE due to the cooling fan power and the losses in the generator.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.225-232
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• 2024

The reduction of CO₂ emissions in the energy production sector, which accounts for 86.8% of total greenhouse gas emissions, is important to achieve carbon-neutrality. At present, 60% of total power generation in South Korea is coal and natural gas. Replacing fossil fuel with renewable energy such as wind and solar has disadvantages of unstable energy supply and high costs. Therefore, this study was conducted through the co-firing of natural gas, ammonia and hydrogen utilizing the natural gas combined cycle process. The results demonstrated reduction in CO₂ emissions and 34%~238% of the power production compared to using only natural gas. Case studies on mass fractions of natural gas, ammonia and hydrogen indicated that power production and NO_x emissions were inversely proportional to the ammonia ratio and directly proportional to the hydrogen ratio. This study provides guidelines for the use of various fuel mixtures and economic analysis in co-firing power generation.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.600-603
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• 2005

U.S. National Research Council proposed benefits framework for energy R&D project as economic benefits, environmental benefits, security benefits and knowledge benefits. Following this framework, U.S. National Renewable Energy Laboratory evaluated the projected benefits of Federal Energy Efficiency and Renewable Energy Programs in the indicators of energy-expenditure savings, energy system cost savings, $CO_2$ emissions reductions. oil savings, natural gas saving and avoided additions to central conventional power. As this result, geothermal energy have predominant position in the energy-expenditure savings, natural gas saving and avoided addi t ions to central conventional power to FY2050. The projected benefits, in monetary value, of the whole supply-potential of geothermal energy in Korea were evaluated as 480.2 billion Won, 43.1 billion Won and 135.8 billion Won for the private energy-cost savings, social environmental-cost savings, and import energy-cost saving, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.339-342
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• 2006

The power outputs of renewable energy such as wind turbines and solar energy powers depend on natural sources. Accordingly, the power outputs of renewable energy is different from capacity rate at the time of peak load. Because of this gap, long term electricity power plan can have over-estimated reserve margin. So, this paper suggests the chronological approach to calculate the reliability assessment of renewable energy.

• Journal of Korea Multimedia Society
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• v.25 no.11
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• pp.1572-1581
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• 2022

Energy conversion to renewable energy is being promoted to solve the recently serious environmental pollution problem. Solar energy is one of the promising natural renewable energy sources. Compared to other energy sources, it is receiving great attention because it has less ecological impact and is sustainable. It is important to predict power generation at a future time in order to maximize the output of solar energy and ensure the stability and variability of power. In this paper, solar power generation data and sensor data were used. Using the PCC(Pearson Correlation Coefficient) analysis method, factors with a large correlation with power generation were derived and applied to the GAM(Generalized Additive Model). And the prediction accuracy of the power generation prediction model was judged. It aims to derive efficient solar power generation in the future and improve power generation performance.