• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1890-1901
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• 2022

We have assessed the applicability of the thermal-hydraulic system analysis code, SPACE, to a small modular reactor called SMART. For the assessment, the experimental data from a scale-down integral-test facility, SMART-ITL, were used. It was conformed that the SPACE code unrealistically calculates the safety injection flow rate through the CMT and SIT during a small-break loss-of-coolant experiment. This unrealistic behavior was due to the overprediction of interfacial heat transfer at the steam-water interface in a vertically stratified flow in the tanks. In this study, a special thermal-hydraulic component model has been developed to realistically calculate the interfacial heat transfer when a strong non-equilibrium two-phase flow is formed in the CMT or SIT. Additionally, we developed a special heat structure model, which analytically calculates the heat transfer from the hot steam to the cold tank wall. The combination of two models for the tank are called the special component model. We assessed it using the SMART-ITL passive safety injection system (PSIS) test data. The results showed that the special component model well predicts the transient behaviors of the CMT and SIT.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.39-47
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• 2007

It is investigated how KOH and Rthylenediamine(EDA) treatment conditions on Polyimide film surface affect the interfacial fracture energy between electroless plated Ni and Polyimide film by $180^{\circ}$ peel test. Estimated values of interfacial fracture energy were 24.5 g/mm and 33.3 g/mm for the KOH treatment times under 1 and 5 minutes, respectively, while, those were 31.6 g/mm and 22.3 g/mm for EDA treatment times under 1 and 5 minutes, respectively. Interfacial bonding between electroless plated Ni and Polyimide seems to be dominated by chemical bonding effect rather than mechanical interlocking effect. It is found that chemical treatment produces carboxyl and mine functional groups which are closely related the interfacial bonding mechanism. Finally, it is speculated that interfacial fracture energy seems to be controlled by O=C-O bonding near cohesive failure region.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.99-105
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• 2002

A finite volume numerical approach is developed and used to simulate convection-dominated melting and solidification problems. The present approach is based on the enthalpy-porosity method that is traditionally used to track the motion of the liquid-solid front and to obtain the temperature and velocity profiles in the liquid-phase. The enthalpy-porosity model treats the solid-phase as the porosity in all computational cells that are located on the solid-liquid interfacial boundary. Concerning the computational cells that are fully located in the solid side of the interfacial boundary, the zero value of the porosity severely suppresses the velocity vector to practically a non-existent value that could be set equal to zero. A comparative analysis with the previous numerical approaches is performed to demonstrate the improved features of the presented model. Results of a melting and solidification experiments are also used to assess and evaluate the performance of the model.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.632-636
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• 2005

In this work, the effect of chemical treatments on surface properties of SiC was investigated in thermal and mechanical interfacial behaviors of SiC/PMMA nanocomposites. The acid/base value, contact angles, and FT-IR analysis were performed for the study of surface characteristics of the SiC studied. The thermal stabilities of the SiC/PMMA nanocomposites were investigated by thermogravimetric analysis (TGA). Also the mechanical interfacial properties of the composites were studied in critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$) measurements. As a result, the acidically treated SiC (A-SiC) had higher acid value than that of untreated SiC (V-SiC) or basically treated SiC (B-SiC). The acidic solution treatment led to an increase in surface free energy of the SiC, mainly due to the increase of its specific component. Thermal and mechanical interfacial properties of the SiC/PMMA nanocomposites, including initial decomposition temperature (IDT), $K_{IC}$, and $G_{IC}$ had been improved in the acidic treatment on SiC. This was due to the improvement in the interfacial bonding strength, resulting from the acid-base interfacial interactions between the fillers and polymeric matrix.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.29-34
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• 2002

[ $Nb/MoSi_2-ZrO_2$ ] laminate composites have been successfully fabricated by alternately stacking $MoSi_2-ZrO_2$ powder layer and Nb sheet, followed by hot pressing in a graphite mould. The fabricating parameters were selected as hot press temperatures. The instrumented Charpy impact test was carried out at the room temperature in order to investigate the relationship between impact properties and fabricating temperatures. The interfacial shear strength between $MoSi_2-ZrO_2$ and Nb, which is associated with the fabricating temperature and the growth of interfacial reaction layer, is also discussed. The plastic deformation of Nb sheet and the interfacial delamination were macroscopically observed. The $Nb/MoSi_2-ZrO_2$ laminate composites had the maximum impact value when fabricated at 1623K, accompanying the increase of fracture displacement and crack propagation energy. The interfacial shear strength of $Nb/MoSi_2-ZrO_2$ laminate composites increased with the growth of interfacial reaction layer, which resulted from the increase of fabricating temperature. there is an appropriate interfacial shear strength for the enhancement of impact value of $Nb/MoSi_2-ZrO_2$ laminate composites. A large increase of interfacial shear strength restrains the plastic deformation of Nb sheet.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.263-267
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• 2001

The changes of interfacial properties and microfailure degradation mechanisms of bioabsorbable composites with hydrolysis were investigated using micromechanical test and acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of PEA and bioactive glass fibers decreased, whereas those of chitosan fiber changed little. Interfacial shear strength (IFSS) of bioactive glass fiber/poly-L-lactide (PLLA) composite was significantly higher than that two other systems. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composite, whereas that of chitosan fiber/PLLA composite was the slowest. With increasing hydrolysis time, distribution of AE amplitude was narrow, and AE energy decreased gradually.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.108-111
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• 2004

The polypropylene(PP) fiber is poised as a low cost alternative for reinforcement in structural applications in comparison with other high performance fibers, such as the polyvinyl-alcohol(PVA), polyethylene, carbon and aramid fiber. The mechanical properties of the composite are strongly determined by the interfacial behavior of fiber and cementitious matrix. The crack bridging mechanism contribute to composite toughness from activation of the fiber-matrix interface where energy is dissipated through debonding of the interface and fiber pullout. In this study, therefore, the pullout behavior of PP fibers is investigated. Experimental work includes the investigation of the interfacial properties, and the composite property. The quantification of interfacial properties, the frictional bond is achieved through single fiber pullout test. A study on the effect of inclination angle on fiber pullout behavior is also conducted.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.359-364
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• 1998

The interfacial zone in concrete materials is extensive, geometrically complex, and constitutes inherently weak zones that limit the concrete performance. Motar-aggregate interfaces play a major role in the fracture processing in concrete composites. Also, the interfacial bond considerably influence mechanical properties of concrete such as modulus of elasticity, strength, and fracture energy, Characterization of the interfacial properties is, therefore, essential to overcome the limitations associated with the interfaces. an objective of this paper is to investigate the corelationship between the fracture toughness of mortar-aggregate interface and the concrete properties such as strengths and elastic moduli. It is observed from the test results that interface fracture toughness is closely related with the compressive strength rather than other properties. At early ages, the development of both tensile strength and elastic modulus are much greater thatn that of both interface fracture toughness and compressive strength.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.88-91
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• 2004

In this study, a number of natural fiber henequen reinforced polymer matrix composites were successfully fabricated by means of a compression molding technique using chopped henequen fibers surface-treated with different electron beam irradiation (EBI) dosages, thermoplastic poly(butylene succinate), thermosetting unsaturated polyester and phenolic resins. Their interfacial and thermal characteristics were studied in terms of interfacial shear strength, fracture surface, dynamic mechanical properties, dimensional stability, and thermal stability using single fiber microbonding test, SEM, DMA, TMA, and TGA. The results show that their interfacial and thermal properties significantly depend on the intensity of EBl treatment on the natural fiber surface.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.981-994
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• 2014

Density currents formed by buoyancy discharges from rivers are numerically studied using non-dimensional two layer model including Coriolis acceleration, bottom stress, interfacial friction. Some typical numbers such as Froude number, densimetric Froude number and Kelvin number are obtained and some characteristic scales are defined as a result of non-dimensionalization of the governing equations. Besides the Coriolis effect, the configurations of bottom topography, bottom friction coefficient and interfacial friction are found to significantly affect the propagation of the warm water plume. Frontal position can fastly propagate in the case of large density difference between the two layers and small interfacial friction. Left side boundary current is easily formed under the small interfacial friction. With large Kelvin number, both right and left side boundary currents are formed. Wave-like disturbances and eddies are easily formed under the high Froude number.