• Carbon letters
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• v.9 no.1
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• pp.47-60
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• 2008

Understanding the exact structure and surface characteristics of carbon materials is very important for design, synthesis, and utilization of the best carbon form with particular functions and high performance for practical applications such as selective adsorption adsorbents, energy storage materials, catalysts or catalyst supports, etc. This review paper focuses on carbon surface properties and the interaction between gaseous or liquid substances and carbon surface. Catalytic functions of carbon materials are reviewed including recent progress in synthesis and applications of nano-carbons.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.673-680
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• 2019

This study investigates the validity of applying new carbon nanotube (CNT, Carbon Nano Tube) surface heaters, which are applied in combination with various products, to the vessel's materials, and proposes the commercializable products accordingly. In order to actually apply a CNT surface heating system technology to the ship's equipment for the first time in Korea, we carried out the interview of experts in the technology field and the due diligence of the shipyard, and presented the technology road map for the selected three items. Finally, for "Heating System of Ship Fuel Tank" with the highest commercialization potential, we proposed a conceptual diagram to enable the final development of the product through the product analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.10
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• pp.1033-1041
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• 2012

Performance evaluation of a direct carbon fuel cell (DCFC) was conducted according to coals and a graphite particle. Several fuel properties such as thermal reactivity, textural structure, gas adsorption characteristic, and functional groups on the surface of fuels were investigated and their effects on electrochemistry were discussed. The strong carbon structure inside of fuels led the rapid potential decreasing in high current density region, because it caused small surface area and low pore volume. The functional groups on the surface were related to the low current density region. The maximum current density and power density of fuels were affected by the total carbon content in fuels. The effect of operating conditions such as stirring rate and operating temperature was investigated in this study.

• Journal of Radiation Industry
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• v.18 no.2
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• pp.133-140
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• 2024

The Korean 2^nd basic plan for management of high-level radioactive waste presented a plan to manage spent nuclear fuel through dry storage facilities in NPP on-site. For the construction and operation of the facility, it is necessary to develop the monitoring system of the integrity of spent nuclear fuel before operation. NUREG-1536 recommends that the theoretical cask array, typically in the 2×10 array, should account for shadowing effect among the dry storage casks. The objective of this study was to evaluate neutron flux accounting for shadowing effect among dry storage casks. The neutron release rate was evaluated using ORIGEN based on the design basis fuel condition. And the simulation of dry storage casks and evaluation of the shadowing effect were performed using MCNP. Shadowing effect of other dry storage casks was the highest at the center of the dry storage facility of the 2×10 array compared with the outside of the cask. The shadowing effect of neutron flux on the surface among the metal casks was approximately 18% at point 1, 23% at point 2, and 43% at point 3. For the concrete casks, the shadowing effect of neutron flux on the surface was approximately 46% at point 1, 51% at point 2, and 52% at point 3. This means that correction is necessary to monitor the integrity of spent nuclear fuel in each dry storage cask through evaluation of shadowing effect. The results of this study will be used for comparative analysis of neutron measurement data from spent nuclear fuels in dry storage cask. Additionally, the neutron flux evaluation procedure used in this study could be used as the basic data of safety assessment of dry storage cask and development of safety guide.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2018-2025
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• 2019

This study systematically compared two hybrid deterministic/Monte Carlo transport codes, ADVANTG/MCNP and MAVRIC, in solving a difficult shielding problem for a real-world spent fuel storage cask. Both hybrid codes were developed based on the consistent adjoint driven importance sampling (CADIS) methodology but with different implementations. The dose rate distributions on the cask surface were of primary interest and their predicted results were compared with each other and with a straightforward MCNP calculation as a baseline case. Forward-Weighted CADIS was applied for optimization toward uniform statistical uncertainties for all tallies on the cask surface. Both ADVANTG/MCNP and MAVRIC achieved substantial improvements in overall computational efficiencies, especially for gamma-ray transport. Compared with the continuous-energy ADVANTG/MCNP calculations, the coarse-group MAVRIC calculations underestimated the neutron dose rates on the cask's side surface by an approximate factor of two and slightly overestimated the dose rates on the cask's top and side surfaces for fuel gamma and hardware gamma sources because of the impact of multigroup approximation. The fine-group MAVRIC calculations improved to a certain extent and the addition of continuous-energy treatment to the Monte Carlo code in the latest MAVRIC sequence greatly reduced these discrepancies. For the two continuous-energy calculations of ADVANTG/MCNP and MAVRIC, a remaining difference of approximately 30% between the neutron dose rates on the cask's side surface resulted from inconsistent use of thermal scattering treatment of hydrogen in concrete.

• Fire Science and Engineering
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• v.24 no.1
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• pp.116-121
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• 2010

The present study has been performed to investigate the ignition characteristics of a n-dodecane fuel droplet on the hot surface. Simplified bench scale test setup was built to examine the effect of air flow on the ignition temperature of fuel droplet. IR pyrometric sensor was used to measure the surface temperature, the measured temperature using IR pyrometer was directly compared with k-type thermocouple. The ignition of n-dodecane fuel droplet was divided into two stage - cool flame and hot flame - with the air flow rate except the case of air flow rate 3.0 lpm. The ignition temperature and probability was greatly affected by the air flow rate and the MHSIT of the present study was about $300^{\circ}C$ for air flow rate of 0.5 lpm.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.484-488
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• 1997

Fission product release (FPR) assessment for 100% reactor outlet header (ROH) break in CANDU reactor loaded with CANFLEX-NU fuel bundles has been performed. The predicted results are compared with those for the reactor loaded with standard 37-element bundles. The fuel failure thresholds for the CANFLEX and standard bundle elements are very similar. All the sheaths at the corresponding fuel failure thresholds for the CANFLEX and standard bundles fail due to the significant cracks in the surface oxide, except those for the CANFLEX inner element at burnups of 220 to 240 MW.h/kg(U), which fail due to the excessive diametral strain. The fuel failure analysis predicts that the number of failed fuel elements for the CANFLEX bundle case is none, while that for the standard bundle case is 1827. The total (gap plus bound) I-131 releases for the CANFLEX and standard bundles are none and 5889 TBq, respectively The significant reduction of the number of failed fuel elements and FPR for the CABFKEX fuel bundle is attributed to the lower linear power of the CANFLEX fuel bundle compared with the standard fuel bundle.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1187-1195
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• 2004

The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated by varying fuel temperature from - 30$^{\circ}C$ to 120$^{\circ}C$ and injection pressure from 0.29 to 0.69 ㎫. Two kinds of fuel having different surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases, the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially different according to the fuel temperature range.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.378-386
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• 2003

Recently failures of nuclear fuel rods in Korean nuclear power plants were reported and their failure causes have been investigated by using PIE techniques. Destructive and physico-chemical examinations reveal that the clad hydriding phenomena had caused the rod failures primarily and secondarily in each case. In this study, the basic mechanisms of the primary and the secondary hydriding failures are reviewed, PIE data such as cladding inner and outer surface oxide thickness and the restructuring of the fuel pellets are analyzed, and they are compared with the predicted behaviors by a fuel performance code. In addition, post-defected fuel behaviors are reviewed and qualitatively analyzed. The results strongly support that the hydriding processes, primary and secondary, played critical roles in the respective fuel rods failures and the secondary hydriding failure can take place even in the fuel rod with low linear heat generation rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.917-920
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• 2003

The sloshing phenomenon sometimes happens to occur in a liquid fuel tank due to the unexpected and/or inevitable vibrating conditions and may result in severe effects on the structural stability. This study deals with the development of experimental techniques for the evaluation of sloshing behaviors in the liquid fuel tank and for the identification of natural frequencies and mode shapes by varying with various vibrating conditions. Measurements of the pressure and load acting on the side surface of vibrated liquid fuel tank are carried in order to identify the effects of sloshing phenomenon by using various types of baffles. The results show that the baffles can be used to minimize the sloshing phenomenon in liquid fuel tank effectively