• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.443-444
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• 2007

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.252.2-252.2
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• 2010

Biomass is considered to be a major potential fuel and renewable resource for the future. In fact, there is high potential to produce the large amount of energy from biomass around the world. In this study, to obtain basic data for practical application of wood pellet and wood pellet boiler system as heating system in agriculture, agricultural biomass resources were surveyed, pellet was made of agricultural by-product such as stem of rape, oat and rice, ricehusk and sawdust and wood pellet boiler system with capacity of 116 kW was manufactured and installed in greenhouse of $38.5m{\times}32m$. High heating value, bulk density and ash content of pellet made of agricultural by-product and efficiency and heating performance of this system was estimated. Rice straw was the largest agricultural biomass in 2005 and the total amount of rice straw converted into energy of $131.71{\times}10^{11}$ kJ. And in 2005, total amount of forest' by-product converted into energy of $29,277.05{\times}10^{11}$ kJ. High heating values of pellets made of agricultural by-products of stem and seed of rape, stem of oat, rice straw and rice husk were 16,034, 16,026, 16,089, 15,650, 15,044 kJ/kg respectively. High heating values of pellets made of agricultural by-products were 83.6% compared to that of wood pellet. Average bulk density of pellets made of agricultural by-products of stem and seed of rape, stem of oat, rice straw and rice husk was 1,400 $kg/m^3$. Ash contents of the pellets were 6.6, 7.0, 6.2, 5.5, 33% respectively. Ash content of rice husk pellet was the largest compared to other kind of pellets. To increase efficiency of agricultural pellet boiler, the boiler adopted secondary heat exchanger. The agricultural pellet boiler designed and manufactured in this study had high efficiency of 84.2% compared to the conventional agricultural pellet boiler, when water flow rate, exhaust gas temperature and average combustion furnace temperature were 39L/min, $180^{\circ}C$, $680^{\circ}C$ respectively. And pellet supplying and pausing time were 13, 43 seconds respectively. In March of 2010, prices of wood pellet, agricultural tax free diesel, diesel, kerosene were 350 won/kg, 811 won/L, 1,422 won/L, 976 Won/L respectively. Also in terms of energy, prices per same heating value were 77.8, 90.1, 158, 108.4 Won/Mcal. Energy saving rate of wood pellet was 16, 50, 39% compared to agricultural tax free diesel, diesel and kerosene respectively.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.90-99
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• 1994

One of the major phenomena occurring in defective fuel rods is the oxidation of UO$_2$ fuel pellets from UO$_2$ to UO$_{2+}$x/ by the oxygen Produced from the dissociation of the steam in the Pellet-to-clad gap, which leads to the enhancement of fission gas release. In this paper, the oxidation kinetics of defective fuel rods was analyzed on the basis of operating conditions of the reactor and defective fuel rod itself. Oxidation kinetics of the fuel pellet was determined under the assumption that the gap is filled with the saturated steam of 150 atm and an enhancement factor for fission gas release was introduced to take into account the effect of fuel oxidation on fission gas release. Comparison with experimental data shows that the enhancement factor predicts well the increased fission gas release due to the oxidation of UO$_2$fuel pellets.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.269-274
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• 2011

A CFD analysis was performed to examine the inner channel blockage of dual-cooled fuel which has being developed for the power uprate of a pressurized water reactor (PWR). The dual-cooled fuel consists of an annular fuel pellet($UO_2$) and dual claddings as well as internal and external cooling channels. The dual-cooled annular fuel is different from a conventional solid 려el by employing an internal cooling channel for each fuel pellet as well as an external cooling channel. One of the key issues is the hypothetical event of inner channel blockage because the inner channel is an isolated flow channel without the coolant mixing between the neighboring flow channels. The inner channel blockage could cause the Departure from Nucleate Boiling (DNB) in the inner channel that eventually causes a fuel failure. This paper presents the CFD simulation of the flow through the side holes of the bottom end plug for the complete entrance blockage of the inner channel. Since the amount of coolant supply to the inner channel depends on largely the pressure loss at the side hole, the pressure loss coefficient of the side hole was estimated by the CFD analysis. The CFD prediction of the loss coefficient showed a reasonable agreement with an experimental data for the complete blockage of both the inner channel entrance and the outer channel. The CFD predictions also showed the decrease of the loss coefficient as the outer channel blockage increases.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.609-616
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• 1992

This study has been investigated on the milling of Aluminium Distearate (ADS) powder and characteristics of the ADS-doped UO2 pellets. As-received ADS powder of the agglomerated particles has not shown any milling effect because of heat generated during planetary milling. But the use of coolant to effectively remove heat generated during milling has been found an effective way in breaking up the agglomerates of ADS powder. The green density of the UO2 pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% theoretical density, the 200 ppm ADS-doped UO2 pellet has to be pressed under higher compacting pressure of 3500~4000 kgf/$\textrm{cm}^2$ compared with the ADS-undoped UO2 pellet pressed under around 3000 kgf/$\textrm{cm}^2$. The ADS-dpoed UO2 pellet with even relatively low sintered density of 10.27 g/㎤ exhibits open porosity of 1% while open porosity of the ADS-undoped UO2 pellet is reduced to around 1% only after its sintered density increases to 10.43g/㎤. It is, therefore, concluded that doping of ADS powder significantly contributes to the decrease in open porosity of the UO2 pellet. The dilatometry of the ADS doped UO2 pellet shows the sintering rate curve with the bimodal mode, which could be attributed to a phase reaction between UO2 and ADS. The X-ray diffraction analysis indicates that there occurs not any new phase formed but the shift of the peaks. It would be expected that a phase reaction resulting in solid solution would happen in the temperature range of 130$0^{\circ}C$ to 150$0^{\circ}C$ between UO2 and ADS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.226-229
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• 2008

To investigate an in-pile behavior of the newly developed DUO fuel pellet, the irradiation test will be carried out in the domestic test reactor. Irradiation test capsule for the HANARO reactor, which is a specially designed equipment used for material, irradiation and creep test, must satisfy the operational requirement on the hydraulic characteristics and structural integrity. In this study, a pressure drop, a flow-induced vibration and a short-term endurance test for the newly developed non-instrumented test capsule were carried out using FIVPET as a out-pile evaluation test. The test results show that the new test rig satisfy the HANARO operational requirement with sufficient margin.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1283-1292
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• 1994

Ultra-fine $\beta$-SiC powders were fabricated by self-propagating high temperature synthesis process (SHS) using chemical furnace. The dependences of the C powders with different surface areas, the molar ratios of C/Si, the weight ratios of chemical fuel content, and pellet diameter-size on synthesis were investigated. Compositional and structural characterization of these powders was carried out by scanning electron micrograph and X-ray diffraction. The $\beta$-SiC powders which had C/Si mole ratio=1.05, 3 times chemical fuel contents, and pellet diameter=20 mm were optimum for synthesis efficiency. By optimizing process-variables, it is possible to fabricate $\beta$-SiC powders which have little secondary phases ($\alpha$-SiC).

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.89-95
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• 2003

Fuel processing is an enabling technology for faster commercialization under lack of hydrogen infrastructures. It has been reported that the development of novel catalysts that are active and selective for hydrocarbon reforming reactions. It has been realized, however, that with pellet or conventional honeycomb catalysts, the reforming process is mass transport limited. This paper reports the development of catalyst structures with microchannels that are able to reduce the diffusion resistance and thereby achieve the same production rate within a smaller reactor bed. These microchannel reforming catalysts were prepared and tested with natural gas and gasoline-type fuels in a microreactor (1-cm dia.) at space velocities of up to 250,000 per hour. These catalysts have also been used in engineering-scale reactors (10 kWe, 7-cm dia.) with similar product qualities. Compared to pellet catalysts. the microchannel catalysts enable a nearly 5-fold reduction in catalyst weight and volume.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.1
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• pp.53-64
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• 2007

The dynamic release behavior of Cs from high burn-up spent PWR fuel was experimentally performed under the conditions of a thermal treatment process such as voloxidation and sintering conditions. In voloxidation process, influence of the oxidation and reduction atmosphere on the Cs release characteristic using fragment type of spent fuel heated up to $1,500^{\circ}C$ was compared. In sintering process, temperature history effect on Cs release behavior was evaluated using green pellet under 4% $H_2/Ar$ environment. Temperature range for complete Cs release from spent fuel fragment under voloxidation condition was about $800^{\circ}C{\sim}1,200^{\circ}C$, but that of green pellet under the reduction atmosphere was $1,100^{\circ}C{\sim}1,400^{\circ}C$. Key parameters on Cs release behavior from spent fuel was powder formation as well as the diffusion rate of Cs compound to grain boundary and fuel surface.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.342.1-342
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• 2001