• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.291-297
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• 2006

Recently it is a tendency that the use of the heavy fuel oil is investigated even from the middle&small class vessel in order to reduce the operating cost of vessel caused by with rise of international gas price. In this study, analyzed the physical & chemical properties and examined the effect of refining treatment and a fuel oil additive for MF30 fuel oil which is a mixture fuel oil mixed M.G.O and the heavy oil MF380 use to be possible in the middle&small class vessel. As a results, the effects of two of pre-refinery treatment methods as centrifugal purifier and heating & homogenizing system(M.C.H) are some feeble, but the pour point and the flash point came to be low more or less. The effect of property improvement which is caused by with the fuel oil additive did not appear positively.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.309-316
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• 2009

The effect of gas diffusion layers (GDLs) on the freeze/thaw condition durability in polymer electrolyte fuel cells (PEFCs) were investigated. For this purpose, three kinds of GDLs, such as, felt, paper and cloth types with different basic properties have been first prepared, then the changes in the properties and performance of cells was observed during the freeze/thaw cycles ranging from -30 to $70^{\circ}C$. The performance evaluations were conducted by using the single cells consisting of different GDLs. The performance degradation and the cell resistance increase could be directly correlated. The physical destruction of electrode was shown by SEM analysis. The mechanically supporting ability on the interface between the cell components can help enhancing the durability of PEFCs in the freeze/thaw condition.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.190-198
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• 2016

Application of fuel cell to produce renewable energy for commercial purpose is limited by the high cost of Pt based electrode materials. Development of inexpensive, high energetic electrode is the need of the hour to produce pollution free energy using bio-fuel through a fuel cell. Ni-Cu and Ni-CeO₂-Cu electrode materials, electro synthesized by pulse current have been developed. The surface morphology of the electrode materials is controlled by different deposition parameters in order to produce a high current from the electro-oxidation of the fuel, the ethanol. The developed materials are electrochemically characterized by Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiodynamic polarization tests. The results confirm that the high current is due to their enhanced catalytic properties viz. high exchange current density (i₀), low polarization resistance (R_p) and low impedance. It is worthwhile to mention here that the addition of CeO₂ to Ni-Cu has outperformed Pt as far as the high electro catalytic properties are concerned; the exchange current density is about eight times higher than the same on Pt surface. The morphology of the electrode surface examined by SEM and FESEM exhibits that the grains are narrow and sub spherical with 3D surface, containing vacancies in between the elongated grains. The fact has enhanced more surface area for electro oxidation of the fuel, giving rise to an increase in current. Presence of Ni, CeO₂, and Cu is confirmed by the XRD and EDXS. Fuel cell fabricated with Ni-CeO₂-Cu material electrode is expected to produce clean electrical energy at cheaper rates than conventional one, using bio fuel the derived from biomass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.1 s.28
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• pp.39-45
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• 2007

Recently it is a tendency that the heavy fuel oil is considered to be used on board even middle or small sized vessels in order to reduce the operating cost of vessel mused by a rise in international oil prices. In this study, analyzed the physical & chemical properties and examined the effect of refining treatment and a fuel oil additive for MF30 fuel oil which is a mixture fuel oil mixed M.G.O and the heavy oil MF380 use to be possible in the middle&small class vessel. As a results, the effects of two of pre-refinery treatment methods as centrifugal purifier and heating & homogenizing system(M.C.H) are some feeble, but the pour point and the flash point came to be low more or less. The effect of property improvement which is mused by the fuel oil additive did not appear positively.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1733-1739
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• 2017

Molecular dynamics simulations were performed to investigate the uniaxial tensile properties of nanocrystalline $U_{0.5}Th_{0.5}O_2$ solid solution with the Born-Mayer-Huggins potential. The results indicated that the elastic modulus increased linearly with the density relative to a single crystal, but decreased with increasing temperature. The simulated nanocrystalline $U_{0.5}Th_{0.5}O_2$ exhibited a breakdown in the Halle-Petch relation with mean grain size varying from 3.0 nm to 18.0 nm. Moreover, the elastic modulus of $U_{1-y}Th_yO_2$ solid solutions with different content of thorium at 300 K was also studied and the results accorded well with the experimental data available in the literature. In addition, the fracture mode of nanocrystalline $U_{0.5}Th_{0.5}O_2$ was inclined to be ductile because the fracture behavior was preceded by some moderate amount of plastic deformation, which is different from what has been seen earlier in simulations of pure $UO_2$.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.518-525
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• 2019

The mechanical and corrosion behavior of the Russian zirconium fuel cladding alloy E110, predominantly used in VVERs, has been investigated for many decades. The recent commercialization of a new, optimized E110 alloy, produced on a sponge zirconium basis, gave the opportunity to compare the mechanical properties of the old and the new E110 fuel claddings. Axial and tangential tensile test experiments were performed with samples from both claddings in the MTA EK. Due to the anisotropy of the cladding tubes, the axial tensile strength was 10-15% higher than the tangential (measured by ring tensile tests). The tensile strength of the new E110G alloy was 11% higher than that of the E110 cladding at room temperature. Some samples underwent chemical treatment - slight oxidation in steam or hydrogenation - or heat treatment - in argon atmosphere at temperatures between 600 and $1000^{\circ}C$. The heat treatment during the oxidation had more significant effect on the tensile strength of the claddings than the oxidation itself, which lowered the tensile strength as the thickness of the metal decreased. The hydrogenation of the cladding samples slightly lowered the tensile strength and the samples but they remained ductile even at room temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.684-687
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• 2002

The authors have developed two devices which cuts the spend fuel rod to an optimal size and extracts fuel pellet from the pieces of cut fuel rods. These devices are so important to reduce radioactive wastes that some advanced countries developed their own methods and devices. The authors have benchmarked from these methods and devices. For spent fuel rod cutting, the tube cutting method has been chosen. some mechanical properties of the fuel tube and pellet has been carefully considered for an optimal cutting size. For fuel pellet extraction, a mechanically extracting method has been adopted. The existing chemical method have turned out to be inappropriate because it produced large amount of radioactive wastes, in spite of its high fuel recovery characteristics. The developed method has an advantage that it can be applied to other fuel rods that have different shapes and sizes. The two devices are set up and operated in the hot cell where people can not go in, so that the devices have been designed to be controlled remotely and modulated for easy maintenance. And the performance of the devices has been tested by using simulated fuel rod. From the experimental results, the devices are supposed to be useful for reducing radioactive wastes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.358-363
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• 2006

In this study, the effects of oxygenated fuel such as ethylene glycol mono-normal butyl ether(EGBE) was investigated both DI and IDI diesel engine. Because EGBE includes oxygen content approximately 27.1 %, it is a kind of oxygenated fuel that the smoke emission of EGBE blending fuel is reduced remarkably compared with commercial diesel fuel. The focus of this study was to investigate the effects of the addition of oxygenated fuel to diesel fuel on the engine-out emissions and the performance. Smoke emissions of all EGBE blends were reduced substantially in comparison with conventional diesel fuel. This study showed that remarkable reduction of smoke with oxygenate blending fuels in diesel engines including DI and IDI combustion method. Besides, this study showed that simultaneous reduction of smoke and NOx emissions could be achieved by oxygenated fuel and EGR method that was applied to decrease NOx emissions increasing with smoke emissions reduction.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.124-129
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• 1998

A sensitivity study has been done to determine the composition of DUPIC fuel from the viewpoint of neutronics fuel design. The spent PWR fuel compositions were generated and fissile contents adjusted by blending fresh uranium after mixing two spent PWR fuel assemblies. The $^{239}$ Pu and $^{235}$ U enrichments of DUPIC fuel were adjusted by controlling the amount of fresh uranium feed and the ratio of slightly enriched and depleted uranium in the fled uranium. Based on the material balance calculation, it is recommended that DUPIC fuel composition be such that spent PWR fuel utilization is more than 90%.. A sensitivity study on the temperature reactivity coefficient of DUPIC fuel has shown that it is desirable to increase the $^{239}$ Pu and $^{235}$ U contents to reduce both the fuel and coolant temperature coefficients. On the other hand, refueling simulations of the DUPIC core have shown that the channel power peaking factor, which is a measure of the reactor trip margin, increases with the total fissile content. Considering these neutronic characteristics of the DUPIC fuel, il is recommended to have enrichments of 0.45 and 1.00 wt% for $^{239}$ Pu and $^{235}$ U, respectively.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.423-424
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• 2005

The performance of HANA claddings was evaluated in out-of-pile conditions. All the performance test results revealed that HANA claddings were superior to the reference claddings such as Zircaloy-4 and A-cladding. Corrosion resistance was improved by 60 to 70% compared to the commercial claddings. Creep, burst, tensile, LOCA, wear and microstructural properties were shown to be as good as the commercial claddings.