• 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.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.506-515
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• 2008

Recently, it is exceedingly required to produce metal powders with tailored shape and phase altogether in order to fabricate high performance functional parts such as magnetic core or electro-magnetic noise suppressor for high frequency usage. Therefore, the collision phenomena of in-flight droplets against chamber wall or neighboring in-flight droplets each other is investigated by a computational method in order to get useful information about how to design the atomizing system and how to tailor process parameters not to make irregular-shaped powders during gas atomization process. As a results, smaller powders, lower melt temperature are known to be favorable for droplets not to collide against chamber wall. In additions, powders of narrower size distribution range, lower droplet generation rate, lower melt temperature, lower gas velocity are desirable to prevent droplet-collisions against neighboring in-flight droplets.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.201-205
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• 2009

Triglyceride solid lipid with medium chain fatty acid, tricaprin (TC), was used as a core matrix of lipid nanoparticles (LN) to solubilize water-insoluble paclitaxel and enhance the stability of nanoparticles by immobilization of incorporated drug in the solid core during storage at low temperature. In the present study, TC-LN containing paclitaxel was prepared by hot melt homogenization method using TC as a core lipid and phospholipids as stabilizers. The particle size of TC-LN containing paclitaxel was less than 200 nm and its zeta potential was around -40 mV. Calorimetric analysis showed TC core could be solidified by freezing and thawing in the manufacturing process in which the hot dispersion should be prepared at elevated temperature and subsequently cooled to obtain solid lipid nanoparticles. The melting transition of TC core was observed at $27.5^{\circ}C$, which was lower than melting point of TC bulk. The particle size of TC-LN remained unchanged when kept at $4^{\circ}C$. Paclitaxel containing TC-LN showed comparable anticancer activity to the Cremophore ELbased paclitaxel formulation against human ovarian (OVCAR-3) and breast (MCF-7) cancer cell lines. Thus, lipid nanoparticles with medium chain solid lipid may have a potential as alternative delivery system for parenteral administration of paclitaxel.

• Structural Engineering and Mechanics
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• v.85 no.6
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• pp.755-764
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• 2023

The article examines the impact response of the sandwich beam furnished by a novel bilayer core as inspired by the woodpecker's head architecture under different repeatedly exerted low-velocity impact loadings by employing the finite element package, ABAQUS. The sandwich beam forms four essential parts comprising bottom and top carbon fiber reinforced polymer laminates encasing bilayer core made of laterally arched solid hot melt adhesive material and aluminum honeycomb. Impact loadings are implemented repeatedly with a steel hemisphere impactor for various impact energies, 7.28 J, 9.74 J, and 12.63 J. Essentially, the commonly concentrated stresses at the impact region are regulated away by the arched core in all considered cases thus reducing the threat of failure. The sandwich beam can resist up to 5 continual impacts at 7.28 J and 9.74 J but only up to 3 times repeated loads at 12.63 J before visible failure is noticed. In the examination of several key impact performance indicators under numerous loading cases, the proposed beam demonstrates favorably up to 1.3-11.2 higher impact resistance efficacies compared to existing designs, therefore displaying an improvement in repeated impact resistance of the new design.

• The Journal of the Petrological Society of Korea
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• v.10 no.1
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• pp.1-12
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• 2001

A small of carbonate rocks and spatially-associated ultramafic rocks uniquely occur in the ulsan iron-serpentine mine of the sourtheastern Kyungsang basin. The study of field geology, core drilling data and stable isotope analysis suggest that the carbonate rocks are carbonatite formed from the melt reflecting intrusive natures. Based on this study, the geology of the Ulsan iron-serpentinite mining area consists of Cretaceous sedimentary, volcanic, granitic ultramafic and carbonate rocks in ascending order. The carbonate and ultramafic rocks show concentric and ellipsoidal shapes at the outcrop and a funnel shape in the cross sectional view. Carbon and oxygen stable isotope analysis show a bimodal pattern rather than a typical mantle pattern, which may indicate that the melt was a secondary melt generated within the crus not in the mantle directly. The uprising of ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crus. Then, the intrusion of the ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crust. Then, the intrusion of the ultramafic melt was followed by the intrusion of the carbonate melt along deep-seated fractures. Well-developed major fractures in this area, fluid inclusion characteristics of the carbonate rocks, the spatial relation between the ultramafic and carbonate rocks and stable isotope data support interpreting the Ulsan carbonate rocks as carbonatite.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.294-298
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• 2008

Snow cover is a potential water resource for later spring and summer seasons as well as a thermal mirror with high reflectivity causing decreases of surface air temperature during cold winter seasons. In this study, current and future changes in Northern Hemisphere snow extent and their potential linkages with atmospheric circulation are examined. The NOAA AVHRR visible snow extent (1967-2006) data as well as observational (NCEP-DOE 1979-2006) and modeled (GFDL 2.1 2081-2100) pressure and surface air temperature data are used. Analyses of observational data demonstrate that the snow extent in meteorological spring (March to April) and summer (June to August) has significantly decreased since the late 1980s. The offset of snow seasons (the timing of snow melt in spring) have also significantly advanced particularly in Europe, East Asia, and northwestern North America. Analyses of pressure fields reveal that the spatial patterns of the earlier snow melt are associated with changes in atmospheric circulation such as the Arctic Oscillation (AO). In the positive winter AO years, multiple positive pressure departure cores in the upper troposphere (200hPa) are observed over the mid-latitude regions from March to mid-April, while a negative pressure departure core (70hPa) prevails over the Arctic Ocean. The reversed anomaly patterns related to later snow melt occur in negative winter AO years. The comparison between current and future thermal spring onsets suggest that snow melt patterns will intensify with larger greenhouse gas emissions, indicating earlier hydrological spring onset.

• Nuclear Engineering and Technology
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• v.38 no.6
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• pp.535-550
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• 2006

The objectives of this paper are twofold to summarize the new findings and confirmed results from the Phebus FPT-1 experimental data and to report useful information to MELCOR users regarding the better use of MELCOR. For the core damage behavior, the early stage of a melt progression was predicted well; however, the late phase models, concerned with fuel dissolution, oxide cladding failure, fuel slumping, rubble debris heat up, effects of burn-up fuel, and so on, still showed limitations in MELCOR. For the fission product behavior, the comparison showed unexpected phenomena, various limitations, unresolved issues, and even absence of models. The issues summarized in this study have revealed the main areas where our endeavors need to be intensified in order to improve our understanding of severe accident phenomena. From the analysis of the Phebus FPT-1 test results, not only new core damage features, such as foaming or core expansion, but also possible new fission product release patterns due to effects from a high burn-up fuel have raised alternative challenging phenomena that should be solved in the next severe accident research phase.

• Nuclear Engineering and Technology
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• v.45 no.6
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• pp.767-790
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• 2013

MAAP4 is a computer code that can simulate the response of a light water reactor power plant during severe accident sequences, including actions taken as part of accident management. The code quantitatively predicts the evolution of a severe accident starting from full power conditions given a set of system faults and initiating events through events such as core melt, reactor vessel failure, and containment failure. Furthermore, models are included in the code to represent the actions that could mitigate the accident by in-vessel cooling, external cooling of the reactor pressure vessel, or cooling the debris in containment. A key element tied to using a code like MAAP4 is an uncertainty analysis. The purpose of this paper is to present a MAAP4 based analysis to examine the sensitivity of a key parameter, in this case hydrogen production, to a set of model parameters that are related to a Level 2 PRA analysis. The Level 2 analysis examines those sequences that result in core melting and subsequent reactor pressure vessel failure and its impact on the containment. This paper identifies individual contributors and MAAP4 model parameters that statistically influence hydrogen production. Hydrogen generation was chosen because of its direct relationship to oxidation. With greater oxidation, more heat is added to the core region and relocation (core slump) should occur faster. This, in theory, would lead to shorter failure times and subsequent "hotter" debris pool on the containment floor.

• Korean Journal of Materials Research
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• v.20 no.12
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• pp.691-698
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• 2010

Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at $180^{\circ}C$ as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.41-46
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• 2007

Recently, the study for filling imbalance in thermoplastic polymer has gradually been increased. However, it is hard to find the researches for filling imbalance of thermoplastic elastomer(TPE). The experiment of filling imbalance was conducted for the three kinds of thermoplastic vulcanizes(TPVs) in the mold with geometrically balanced runner system. In this experiment, the effects of the melt temperature and injection speed on the filling imbalance were investigated. To solve the filling imbalance, Runner Core pin(RC pin) in the experimental mold was adopted and it's effects was tested. In this paper, we present that the insert length of RC pin is dependent to each polymers for optimal filling balance.