• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.113-120
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• 2019

We have developed 1 kW-class PEMFC-battery hybrid system independently powering to the building, through the process of system design, current load characteristics analysis, power system configuration for demonstration site and performance evaluation. In order to use the fuel cell and battery as the hybrid type, a control technology for the charging/discharging decision and charging speed of the battery is required rather than using fuel cell. Also output power distribution between PEMFC and the battery is a core of energy management technology. It is confirmed that it is possible to supply independently 1kW powering the building to ensure optimal energy management through the power control experiment of the hybrid system.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.230-239
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• 2024

Efforts are being made to replace ship diesel engines with electric propulsion motors in response to emission regulations. In particular, in the case of short-range small ships, research is being conducted to replace polymer electrolyte membrane fuel cells (PEMFC) with power sources. However, PEMFC has problems such as slow dynamic response characteristics and reduced durability at high temperatures. To solve this problem, a high-precision ship model was developed with power distribution and thermal management strategies applied, and through this, the required power, heat, and power characteristics of the propulsion system according to the ship's speed profile were analyzed.

• Knowledge Management Research
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• v.24 no.1
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• pp.127-145
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• 2023

This paper analyzed a patent trend for technological domain of hydrogen fuel cell, can improve future energy and pollution problems. Patent analysis is used in establishing a technological roadmap which it can discover the current technology capability and future technological development direction. However, the previous patent analysis is qualitative analysis and simple statistical analysis. The reason why it incorrectly analysis patent does not reflect the current technology environment. The current technology environment is development through recombination of technologies. In addition to, the speed of technological development is rapidly growing. So, qualitative analysis does not satisfy the analysis requirements of the times. This paper utilized KP(Knowledge Persistence)-based main path analysis and text mining methods to reflect the current technological environment. As a result, we found core patents, main technology development, and promising technologies for technological domain of the hydrogen fuel cell.

• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.75-86
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• 2024

Hydrogen has been selected as one of the key technologies for reducing CO₂ emissions to achieve carbon neutrality by 2050. However, hydrogen safety issues should be fully guaranteed before the commercial and widespread utilization of hydrogen. Here, a bow-tie risk assessment is conducted for the hydrogen fuel supply system in a gas turbine power plant, which can be a mass consumption application of hydrogen. The bow-tie program is utilized for a qualitative risk assessment, allowing the analysis of the causes and consequences according to the stages of accidents. This study proposed an advanced bow-tie method, which includes the barrier criticality matrix and visualized maps of quantitative risk reduction. It is based on evaluating the importance of numerous barriers for the extent of their impact. In addition, it emphasizes the prioritization and concentrated management of high-importance barriers. The radar chart of a bow tie allows the visual comparison of risk levels before/after the application of barriers (safety measures). The risk reduction methods are semi-quantitatively analyzed utilizing the criticality matrix and radar chart, and risk factors from multiple aspects are derived. For establishing a secure hydrogen fuel storage system, the improvements suggested by the bow-tie risk assessment results, such as 'Ergonomic equipment design to prevent human error' and 'Emergency shutdown system,' will enhance the safety level. It attempts to contribute to the development and enhancement of an efficient safety management system by suggesting a method of calculating the importance of barriers based on the bow-tie risk assessment.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.331-337
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• 2017

A simple strategy is proposed herein for attaining uniform current distribution in direct methanol fuel cells by varying the catalyst loading over the electrode. In order to use the same total catalyst amount for a serpentine flow field, three spatial variation types of catalyst loading were selected: enhancing the cathode catalyst loading (i) near the cathode outlet, (ii) near the cathode inlet, and (iii) near the lateral areas. These variations in catalyst loading are shown to improve the homogeneity of the current distribution, particularly at lower currents and lower air-flow rates. Among these three variations, increased loading near the lateral areas was shown to contribute most to achieving a homogenous current distribution. The mechanism underlying each catalyst loading variation method is different; very high catalyst-loading is shown to decrease the homogeneity of the distribution, which may be caused by water management in the thick catalyst layer thereof.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1854-1858
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• 2007

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, which is carried out to obtain basic dynamic characteristics of the fuel assembly, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification cation for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. Finally, to verify the test result to represent the accurate natural characteristics of the structure, the proper correlation analysis between the theoretical and experimental method has to be carried out. In this study, the overall procedure and result of lateral vibration test for the fuel assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.174.1-174.1
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• 2011

Biogas production and utilisation is an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy services such as heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded, that is, mainly the removal of carbon dioxide to increase the methane content, up to more than 95% in some cases, similar to the composition of fossil-based natural gas. Biogas fuelled vehicles can reduce $CO_2$ emission by between 75% and 200% compared with fossil fuels. Biomethane development is largely driven by national initiative and predominately by concerns for national air pollution and waste management. Recently, biogas projects for vehicle fuels by some companies are ongoing and Korea government also announced investment to develop biogas as a transport fuel. Therefore, the aim of this study is to examine the feasibility of biomethane as a transport fuel in Korea. In this study, we investigated quality characteristics, quality standard and upgrading technology to use vehicle fuel of transport sector in Korea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.3
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• pp.195-207
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• 2012

Fuel consumption in fisheries is a primary concern due to environmental effects and costs to fishermen. Much research has been carried out to reduce the fuel consumption related to fishing operations. The fuel consumption of fishing gear during fishing operation is generally related to hydrodynamic resistance on the gear. This research demonstrates a new approach using numerical methods to reduce fuel consumption. The results from the simulation were verified with results that mirrored the model experiments. By designing the fishing gear using drawing software, the whole and partial resistance force on the gear can be calculated as a result of simulations. The simulation results will suggest suitable materials or gear structure for reducing the hydrodynamic forces on the gear while maintaining the performance of the gear. Furthermore, the efficiency of low energy used trawl as economic point of view will be dealt. This research will helpful to reduce the GHG emissions from fishing operations and lead to reduce fishing costs due to fuel savings.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.320-325
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• 2013

TUnitized reversible fuel cells (URFC) combine the functionality of a fuel cell and electrolyzer in one unitized device. For a URFC with proton exchange membrane, a titanium (Ti)-felt is applied to the gas diffusion layer (GDL) substrate at the oxygen electrode, and additionally titanium (Ti)-powders and TiN-powders are loaded in the GDL substrate as a micro porous layer (MPL). Double porous layer with TiN MPL was not acceptable for the URFC because both of fuel cell performance and electrolysis performance are degraded. The double porous layer with Ti-powder loading in the Ti-felt substrate influence rearly for the electrolysis performance. In contrast, the change of pore-size distribution brings a significant improvement of fuel cell performance under fully humidification conditions. This fact indicates that the hydrophobic meso-pores in the GDL play an important role for mass transport.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.313-323
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• 2010

Fuel consumption in fisheries is a primary concern due to environmental effects and costs to fishermen. Much research has been carried out to reduce the fuel consumption related to fishing operations. The fuel consumption of fishing gear during fishing operation is generally related to hydrodynamic resistance on the gear. This research demonstrates a new approach using numerical methods to reduce fuel consumption. By designing the fishing gear using drawing software, the whole and partial resistance force on the gear can be calculated as a result of simulations. The simulation results will suggest suitable materials or gear structure for reducing the hydrodynamic forces on the gear while maintaining the performance of the gear. This research will helpful to reduce the $CO_2$ emissions from fishing operations and lead to reduce fishing costs due to fuel savings.