• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2839-2844
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• 2008

A PEMFC(proton exchange membrane fuel cell) is a good candidate for residential power generation to be cope with the shortage of fossil fuel and green house gas emission. The attractive benefit of the PEMFC is to produce electric power as well as hot water for home usage. Typically, thermal management of vehicular PEMFC is to reject the heat from the PEMFC to the ambient air. Different from that, the thermal management of PEMFC for RPG is to utilize the heat of PEMFC so that the PEMFC can be operated at its optimal efficiency. In this study, dynamic thermal management system is modeled to understand the response of the thermal management system during dynamic operation. The thermal management system of PEMFC for RPGFC is composed of two cooling circuits, one for controling the fuel cell temperature and the other for heating up the water for home usage. Dynamic responses and operating strategies of the PEMFC system are investigated during load changes.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.361-365
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• 2005

Since the fuel cell uses the hydrogen for its fuel. it has no emission and higher efficiency than an internal combustion engine. Also fuel cell is much quieter than engine generator and generates heat much less than engine generator. So it has advantage of Army's 'si lent watch' capability and the ability to operate undetected by the enemy. The fuel cell hybrid system combines a fuel cell power system with an ESS. The ESS (e.g., batteries or ultracapacitors) reduces the fuel cell's peak power and transient response requirements. It allows the fuel cell to operate more efficiently and recovery of vehicle energy during deceleration. The battery has high energy density, so it has the advantage regarding driving distance. However, it has a disadvantage considering dynamic characteristic because of low power density. One other hand. the ultracapacitor has higher power density, so it can handle sudden change or discharge of required power. Yet. it has lower energy density. so it will be bigger and heavier than the battery when it has the same energy. This paper proposes the power management strategy for multi-power source fuel cell hybrid system. which is applied with the merits of both battery and ultra capacitor by using both of them simultaneous.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.101-104
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• 2006

Water management is considered to be one of the main issues to be addressed for the performance improvement of proton exchange membrane (PEM) fuel cell. For good water management, the detailed information on the water distribution inside an operating PEM fuel cell should be available to main an adequate level of hydration in the PEM While avoiding performance decline due to liquid rater flooding. For the PEM fuel cell to be commercially viable as vehicle applications, the flooding on the cathode side should be minimized during the fuel ceil operation. In this study to investigate cathode flooding and its relation with temperature distribution in flow channels, visualization study was performed on the cathode side of a PEM fuel cell. For the direct visualization of temperature field and water transport in cathode flow channels, a transparent cell was designed and manufactured using quartz window. Water transport and its two-phase flow characteristics in flow channels were investigated experimentally. Also, the visualization of temperature distribution In cathode flow channels was made by using IR camera. Results indicated that the temperature rise near the exit of cathode flow channel was found. It is found that this area corresponds to the flooding area from both temperature and flooding visualization results It is expected that this study can effectively contribute to get the detailed data on water transport linked with heat management during the operation of a PEM fuel cell

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.52-56
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• 2010

Crown fuel characteristics such as crown bulk density, crown base height, and fuel moisture content of Japanese red pine were analyzed. Ten trees in Mt. Palgong at Daegu, were destructively sampled and their crown fuels were weighed separately for each fuel category. Fuel content of live and dead crown component were 53%, and 15.3%, respectively. Foliar moisture content was 56%. Needles and twigs with diameter less than 1cm diameter accounted for 16.2%, 55% of total and crown fuel load. Average crown bulk density of Japanese red pine was 0.24 kg/$m^3$, effective crown fuel bulk density was 0.1325 kg/$m^3$.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.79-87
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• 2024

The Korean launch vehicle (KSLV-II) has used commercial aviation jet fuel, Jet A-1. Fuel specifications were introduced from Jet A-1 specifications. However, specifications and inspection methods of moisture and particulate matters were changed digitally for convenience and accuracy. To control fuel quality, a fuel management system was established to determine suitability by inspecting it at each stage of warehousing, storage, and application. An analysis room was then established at the Naro Space Center. The possibility of fuel mixing was blocked by warehousing inspection. Long-term component changes were then observed by storage inspection. Finally, suitability of the engine test or the launch vehicle test was determined through application inspection. Long-term analysis verified that the space center's fuel oil storage method was appropriate and that the quality management system was able to handle hundreds of engine tests and several flight tests.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.653-658
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• 2010

Biodiesel is well known for an eco-friendly alternative fuel for petrodiesel. But biodiesel has a disadvantage since it is derived from expensive food resource. In this study, we synthesized the biodiesel from duck's oil which was food trash via transesterification under base catalyst. After analytic result of density, kinematic viscosity, cold temperature characteristics, lubricity and cetane number which were main fuel characteristics, this duck's biodiesel has enough potential to use as fuel except only domestic winter season.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.49-62
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• 2009

Social Acceptance is important to decide policy of spent nuclear fuel management. The idea of a public sphere as a receptacle of dynamic process is the core in this discussion. The purpose of this study is to examine the concept, participants, the conflict-structure and agreeable conditions of a public sphere. A public sphere means in this paper, mechanism and systems that various stakeholders' and public's participation with spontaneous will can affect decision-making process. For good designing and implementing a public sphere, it is necessary to analysis and cope with political, foreign and security, economic, sociocultural environments, the law and systems around spent nuclear fuel management.

• Tribology and Lubricants
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• v.28 no.6
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• pp.321-327
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• 2012

Paraffin bio-based hydrotreated biodiesel(HBD) is originated from vegetable oil(the process can also be applied to animal fat) with the the chemical structure $C_nH_{2n+2}$. In the number of process of the oil or fat, the hydrogenation is significantly important to create a bio-based diesel fuel. This study is focused on lubricity characteristics of BTL diesel blends to use alternative diesel fuel in Korea. The BTL diesel are blended the different volume ratios (HBD 5(5 vol.% HBD - 95 vol.% diesel), HBD 10, HBD 20, HBD 30, HBD 40 and HBD 50. HBD with paraffin compounds showed a very high centane number, low sulfur content and free aromatic compound. Especially, the wear scar of HBD showed poor lubricity compared to automotive diesel due to the fuel composition, low sulfur content and free aromatic compound. Also, the lubricity specification of automotive diesel with different six HBD blends is within the limit by the Korean standards. Finally, HBD as an alternative diesel fuel is challengeable in transportation sector of Korea.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.106-111
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• 2005

In nuclear power plant, the source of the energy is generated from the nuclear fuel rod. Given a certain level of consumption, the burnt fuel rod should be removed and replaced by a new(fresh) one. The burnt fuel is approximately one third of the whole fuel rods. Currently, this operation is done manually using paper documents and verbal communication and consumes a lot of operation time. In this study, we develop an computerized operation process of nuclear fuel rod replacement procedure based on the ERP(Enterprise Resource planning) methodology.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.13-16
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• 2007

Fuel cell was used as a propulsion system for unmanned aerial vehicles (UAV) in the present study. Fuel cell propulsion system are an ideal alternative power source with high energy density for high-endurance UAV. Fuel cell power system provides UAV up to five times the energy densiη of existing batteries. Sodium borohydride, stored in liquid state, was selected as a hydrogen source. Hydrogen generation system consists of catalytic reactor, pump, fuel cartridge, and separator. Hybrid power management system (PMS) between fuel cell and lithium-polymer ba야ery was developed. Motor, pump, and fans， operated on battery power controlled by feedback signals of fuel cell system. Battery was recharged by surpuls powr of fuel cell.