• Textile Coloration and Finishing
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• v.25 no.2
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• pp.110-117
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• 2013

The purpose of this study is to fabricate the flame retardant polyester fabric by thermal bonding with low melting component of flame retardant bicomponent filament(LMFRPC) and to describe the characteristics of thermal bonded fabrics. The fabrics were prepared with flame retardant polyester filaments(FRP) as warp and blended filaments of FRP and LMFRPC as weft. The LMFRPC have a sheath and a core wherein the core comprises a flame retardant polyester and the sheath comprises a thermoplastic polyester of low-melting point. In this study, we investigated the physical properties, melting behavior of filament, the effect of the component of FRP and LMFRPC on the thermal bonding, mechanical properties. Melting peak of LMFRPC showed the double melting peak. The thermal bonding of the fabric formed at lower melting peak temperature of bicomponent filament of LMFRPC. The optimum thermal bonding conditions for fabrics was applied at about $170^{\circ}C$ for 60 seconds by pin tenter. On the other hand, the tensile strength, elongation, and LOI of the fabric increased with an increasing component of FRP of weft.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.577-588
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• 1995

A numerical study is made on the melting process of an unconstrained ice inside an isothermal ice-ball capsule. The unmelted ice core is continuously ascending on account of buoyancy forces. Such a buoyancy-assisted melting is commonly characterized by the existence of a thin liquid film above the ice core. The present study is motivated to present a full-equation-based analysis of the influences of the initial subcooling and the natural convection on the fluid flow associated with the buoyancy-assisted melting. In the light of the solution strategy, the present study is substantially distinguished from the existing works in that the complete set of governing equations in both the melted and unmelted regions are resolved in one domain. Numerical results are obtained by varying the wall temperature and initial temperature. The present results reported the transition of the flow pattern in a spherical capsule, as the wall temperature was increased over the density inversion point. In addition, time wise variation of the shapes for the liquid film and the lower ice surface, the time rate of change in the melt volume fraction and the melting distance at symmetric line is analyzed and is presented.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.973-979
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• 2024

In the framework of the Generation IV research and development project, in which the French Commission of Alternative and Atomic Energies (CEA) is involved, a main objective for the design of Sodium-cooled Fast Reactor (SFR) is to meet the safety goals for severe accidents. Among the severe ones, the Unprotected Transient OverPower (UTOP) accidents can lead very quickly to a global melting of the core. UTOP accidents can be considered either as slow during a Control Rod Withdrawal (CRW) or as fast. The paper focuses on fast UTOP accidents, which occur in a few milliseconds, and three different scenarios are considered: rupture of the core support plate, uncontrolled passage of a gas bubble inside the core and core mechanical distortion such as a core flowering/compaction during an earthquake. Several levels and rates of reactivity insertions are also considered and the thermal-mechanical behavior of an ASTRID fuel pin from the ASTRID CFV core is simulated with the GERMINAL code. Two types of fuel pins are simulated, inner and outer core pins, and three different burn-up are considered. Moreover, the feedback from the CABRI programs on these type of transients is used in order to evaluate the failure mechanism in terms of kinetics of energy injection and fuel melting. The CABRI experiments complete the analysis made with GERMINAL calculations and have shown that three dominant mechanisms can be considered as responsible for pin failure or onset of pin degradation during ULOF/UTOP accident: molten cavity pressure loading, fuel-cladding mechanical interaction (FCMI) and fuel break-up. The study is one of the first step in fast UTOP accidents modelling with GERMINAL and it has shown that the code can already succeed in modelling these type of scenarios up to the sodium boiling point. The modeling of the radial propagation of the melting front, validated by comparison with CABRI tests, is already very efficient.

• Fashion & Textile Research Journal
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• v.11 no.4
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• pp.661-666
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• 2009

The purpose of this study is to analyze the dyeability of polyester(PET) fabric by thermal bonding with low melting component of bicomponent fiber and to describe the change of physical properties of thermal bonded PET fabrics. The PET fabrics were prepared with regular PET fiber as warp and bicomponent fiber as weft. The bicomponent fiber of sheath-core type was composed with a regular PET core and low melting PET sheath. The thermal bonding of PET fabric was carried out in pin tenter($195^{\circ}C$) for 60 seconds. In this study, we investigated the dye ability and fastness of the dyed PET fabric. Dye ability of E-type dyestuff is higher than S-type dyestuff. In the case of E- type dyestuff, the saturated dyeing time was 10minutes at $130^{\circ}C$. The washing fastness and light fastness were excellent as 4-5grade.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.191-198
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• 2014

In this paper, structural integrity evaluation of reactor pressure vessel bottom head without penetration nozzles in core melting accident has been performed. Considering the analysis results of thermal load, weight of molten core debris and internal pressure, thermal load is the most significant factor in reactor vessel bottom head. The failure probability was evaluated according to the established failure criteria and the evaluation showed that the equivalent plastic strain results are lower than critical strain failure criteria. Thermal-structural coupled analyses show that the existence of elastic zone with a lower stress than yield strength is in the middle of bottom head thickness. As a result of analysis, the elastic zone became narrow and moved to the internal wall as the internal pressure increases, and it is evaluated that the structural integrity of reactor vessel is maintained under core melting accident.

• Nuclear Engineering and Technology
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• v.35 no.2
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• pp.91-107
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• 2003

Since DBA(Design Basis Accidents) has been studied rather separately from SA(Severe Accidents) in the conventional nuclear reactor safety analysis, the thermal hydraulics during transition between DBA and SA has not been identified so much as each accident itself. Thus, in this study, the thermal hydraulic behavior from DBA to the commencement of SA has been experimentally and analytically investigated for the long-term cooling phase of LB-LOCA(Large-Break Loss-of-Coolant Accident). Experiments were conducted for both cases of the loop seal open and closed in an integral test loop, named as SNUF (Seoul National University Facility), which was scaled down to l/6.4 in length and 1/178 in area of the APR1400 (Advanced Power Reactor 1400MWe). The core mixture level was a main measured value since it took major role in the fuel heat-up rate, the location of fuel melting initiation and the channel blockage by melting material during SA. Experimental results were compared to MAAP4.03 to assess its model of calculating the core mixture level. MAAP4.03 overestimates the core two- phase mixture level because sweep-out and spill-over and the measures to simulate the status of loop seal are not included, which is against the conservatism. Thus, it is recommended that MAAP4.03 should be improved to simulate the thermal hydraulic phenomena, such as sweep-out, spill-over and the status of loop seal.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.3
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• pp.404-414
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• 2014

This study investigates the dyeability and fastness of jacquard fabric for blind using low-melting flame retardant polyester. Two types of jacquard fabric were prepared with a low-melting flame retardant polyester and regular polyester. The low-melting flame retardant polyester has a sheath and a core. The core consists of flame retardant polyester and the sheath consists of low-melting polyester. Disperse red 50 (DR 50), disperse blue 56 (DB 56), disperse yellow (DY 54) of E-type dyes and disperse 92 (DR 92), disperse blue 60 (DB 60), disperse yellow (DY 79) of S-type dyes were used and dyed on jacquard fabrics dependent of dyeing temperature and time. The fastness, dye exhaustion, color strength (K/S value), and colorimetric properties of jacquard fabrics were evaluated. The dyeability of S-type dyes were higher than E-type dyes. The experiments indicated optimum dyeability that the dyeing temperature was $110^{\circ}C$ for E-type dyes and $120^{\circ}C$ for S-type dyes for 40 minutes. The fastness to washing and light were excellent at a 4-5 grade.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2079-2087
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• 1993

The effects of subcooling and natural convection are studied numerically on the melting process of an initially subcooled phase-change medium filled inside a horizontal circular cylinder. It is postulated that melting continues with the tube wall kept at a constant temperature and with the unmelted solid core fixed. Primary emphasis is placed on the evolution of interface morphology, the local/overall heat transfer rate at the tube wall and at the interface, and the structure of natural convection. The numerical results are mainly presented in terms of the Rayleigh and subcooling numbers. As the degree of subcooling intensifies, the melting rate and the movement of the interface are impeded but the interfaces are of similar shape with the passage of time. The heat transfer characteristics are found to be mostly governed by the formation pattern of natural convection in the liquid phase. Good agreement with available experimental data is found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.14-16
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• 2002

Melting and re-solidification nature of $SmBa_2Cu_3O_{7-y}$ (Sm123) grains in Ba-Cu-O (Ba:Cu=3:5) liquid containing 0.7 at.% yttrium were investigated at the temperature lower than its melt point. When Sm123 grains/liquid powder compacts were heated to a temperature between two melting points of Ba-Cu-O liquid ($1000^{\circ}C$) and a Sm123 phase ($1060^{\circ}C$) and held at this temperature for appropriate time, Sm123 grains melted partly in the liquid that was formed by melting of the liquid-forming powder. During subsequent slow cooling, (Sm,Y)$Ba_2Cu_3O_{7-y}$ solidified at the outer parts of the unmelted Sm12 grains, which is distinguished from the core regions by lower $Sm_2BaCuO_5$ (211) density.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.115-119
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• 2020

Selective Laser Melting (SLM) technology is state-of-the-art additive manufacturing process technology that produces a three-dimensional structure by irradiating a laser on a fine metal powder to perform the fusion of a specific area and repeat this process. Owing to the characteristics of the additive manufacturing process, the melting phenomenon of the metal material by the laser has directionality depending on the process conditions, such as the irradiation direction of the laser and the build-up direction. For this reason, the composition of the metal material in the structure exhibits non-uniform characteristics. In this study, aluminum (AlSi10Mg) specimens were manufactured by applying SLM technology, and the material composition characteristics of the specimen were analyzed. The specimens were manufactured as cylinders by the build-up orientation of 0°, 45°, and 90°. The surface morphology of the specimen plane was analyzed optically. TEM analysis was performed on the core and the interface of the melting-pool inside the specimen generated by laser irradiation. The analysis results confirmed that there was a difference between the nano cell structure of the core and the interface of the melting-pool, and that the composition ratio of Si appeared higher at the interface than at the core of the cell.