• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.322-322
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• 2016

Phase change memory (PCM) has attracted much attention as one of the most promising candidates for next-generation nonvolatile memory. In that regard, the purposes of the study are to propose reference of effective pulse parameter to control phase switching operation and to invest the effect of nitrogen doped in PCM materials for improved cycling stability and economic energy consumption. Switching operation of PCM is affected by electric pulse parameter and as shown in figure.1 are composed to RT(rising time), ST(setting time), FT(falling time) and the effect of these parameter was precisely investigated. Transmission electron microscope (TEM) was used to confirm fine structure and retention cycle test was conducted to confirm reliability. Finally improvement reliability and economic power consumption in quantitatively are obtainable by optimum pulse parameter and nitrogen doping in GST material. these study is related to the engineering background of other semiconductor industries and it have confirmed to possibility further applications.

• Fibers and Polymers
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• v.2 no.2
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• pp.81-85
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• 2001

The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.

• Polymer(Korea)
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• v.32 no.4
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• pp.305-312
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• 2008

A novel TPC-PEG-TPC with active end-groups was obtained from the end-groups of polyethylene glycol (PEG) modified by terephthaloyl chloride (TPC). These active end-groups can link up with a rare earth ion, which is a luminescent center of a rare earth fluorescent complex. Complexes of Eu-PEG with novel ligands (TPC-PEG-PTC) were synthesized by the coordination of the active reactant (as the first ligand) and phenanthroline (as the second ligand) with $Eu^{3+}$.IR, $^1H$-NMR, element analysis, DSC, WAXD, fluorescent spectroscopy, TGA, and SEM were used to characterize the structure and properties of these complexes. The results showed that this type of complex is a heat storage material with the phase change character of polyethylene glycol (PEG) and the luminescent properties of europium. There was no thermal decomposition of the complex of Eu-PEG until $300^{\circ}C$. SEM showed that the complex of Eu-PEG can be dispersed in PE.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.982-987
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• 2011

In this study, $Ge_8Se_{(2+x)}Te_{(6-x)}$ thin film amorphous-to-crystalline phase-change rate was evaluated in using a nano-pulse scanner. The focused laser beam with a diameter <10 ${\mu}m$ was illuminated in the power (P) and pulse duration (t) ranges of 1-31 mW and 10-460 ns, respectively, with subsequent detection of the responsive signals reflected from the film surface. We also evaluated the material characteristics, such as optical absorption and energy gap, crystalline phases, and sheet resistance of as-deposited and annealed films. The result of experiments showed that the thermal stability of the Ge-Se-Te film is largely improved by adding Se.

• Solar Energy
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• v.12 no.1
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• pp.48-58
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• 1992

In the present investigation, experimental analysis was performed to research heat transfer phenomena generated by means of conduction and natural convection at a succession of tube-inclimations relative to the vertical tube during inward melting process of a phase change material. The phase change material used in the experiments is 99 percent pure n-docosane paraffin($C_{22}H_{46}$). When the tube is vertical, the dominant mode of energy transfer between the tube wall and the melting interface is natural convection. On the other hand, when the tube is inclined to the vertical, the melting solid is brought into direct contact with the tube wall by the action of gravity. In the experimental results, direct contact gave rise to substantial enhancements in the amount of melted mass, relative to those for natural-convection-dominated melting.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.6
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• pp.767-775
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• 2004

In order to evaluate physiological responses and comfort sensation of the developed thermoregulating textile material, polyester knit fabric was treated with phase change material (PCM) microcapsules by printing. Ten male subjects wearing an experimental best with and without PCMs were seated for 20 minutes, then exercised for 20 minutes, and then seated for 30 minutes in the chamber which was controlled under the temperatures of 20$\pm$1$^{\circ}C$, 50$\pm$5%R.H. The subject's skin temperature, microclimate inside garment and comfort sensation of two experimental bests were compared one another. As a result, the rectal temperature, skin temperature and mean skin temperature were similar in the two groups, and the subjects were not able to perceive the differences in comfort of the two experimental bests. However, the effect of PCM microcapsule could be seen from microclimate temperature and humidity. The microclimate temperature of the PCM garment at chest was significantly higher during exercise. The microclimate humidity of the PCM garment at chest was significantly lower during exercise and rest.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.647-653
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• 2013

TABS (Thermally Activated Building System) has recently applied by huge commercial buildings, airports, and convention centers in Europe. TABS provides night-time thermal storage by heating or cooling. The embedded water-based heating and cooling system uses the high thermal inertia of concrete in the building construction, in which a heating or cooling pipe is embedded. The aim of this study is to analyze the thermal storage and thermal output of TABS applied with PCM (Phase Change Material). To achieve this, prototypes of TABS and the thermal properties of various PCMs were investigated. By using the simulation program Physibel Voltra 6.0 W, the thermal storage and thermal output were evaluated according to a heating and cooling operation schedule.

• Solar Energy
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• v.6 no.2
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• pp.43-53
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• 1986

The objective of this study is to report on the characterics of convective flow and heat transfer during metling process in order to provide design information for thermal energy storage systems which use phase change material. In present study, flow and heat transfer characteristics of the Phase Change Material in the Open Top Model (O.T.M) and in the Closed Top Model (C.T.M) were studied numerically by the control volume formulation using the algebraic non-orthogonal coordinate transformation. For the calculation procedure, the physical properties of fluid are assumed to be constant except density which is linely dependent on temperature in the bouyancy term of momentum equations. At start of melting process, the thickness of melting layer is assumed from the Stefan Problem assumption. The heat transfer results of Open Top Model and Closed Top Model are compared with the parameters of Grashof number and aspect ratio. It was found that heat transfer phenomena in melted region was greatly affected by buoyancy-driven natural convection and the melting distance of Open Top Model at the upper region is greater than that of Closed Top Model.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.183-189
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• 2020

The purpose of this study is to investigate the compressive and tensile properties of high volume slag cement-based fiber-reinforced composite incorporating phase change material. Four mixtures were determined according to calcium hydroxide and expansive admixture, and the compressive strength and tension tests were performed. Test results showed that four mixtures showed a compressive strength over 51MPa and a tensile ductility over 3.2%. It was observed that calcium hydroxide and expansive admixture influenced the compressive and tensile performance, and the strength, ductility, and cracking patterns of composite could be improved by including proper amount of calcium hydroxide and expansive admixture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.154-155
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• 2007

PRAM(Phase-Change RAM) is a promising memory that can solve the problem of conventional memory and has the nearly ideal memory characteristics. We reviewed the issues for high density PRAM integration. Writing current reduction is the most urgent problem for high density PRAM realization. So, we studied new constitution of $Ge_1Se_1Te_2$ chalcogenide material and presented the method of reducing the contact size between $Ge_1Se_1Te_2$ and electrode. A small-contact-area electrode is used primarily to supply current into and minimize heat loss from the chalcogenide. In this letter, we expect the method of reducing the contact size between $Ge_1Se_1Te_2$ and electrode to decrease writing current.