• Title/Summary/Keyword: Melting point

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High $T_c$, Superconductors for Applications

  • Soh, Deawha;Fan, Zhanguo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.05a
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    • pp.366-369
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    • 2003
  • High T$_{c}$ superconducting lines will be applied as key materials in the areas of power transmission line; magnetic levitation of vehicle; magnetic separation; magnetic energy storage and marine propulsion. A combination method of electrophoresis deposition and zone-melting for preparation of YBaCuO tape is proposed. The submicron particle powder of YBaCuO made by sol-gel method is used in the electrophoresis process. A 40~50${\mu}{\textrm}{m}$ thickness of YBaCuO film on Ag plate could be deposited in about three minutes. After deposition the film is rolled and heat treated in order to increase the density and the adhesion of the film to the Ag plate. Silver(Ag) and lead oxide(PbO) were added in the YBaCuO powder in order to reduce its melting point. The YBaCuO coating with controlled Ag and PbO contents was preliminarily zone-melted at about 945$^{\circ}C$.>.

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Dyeing of Thermal Bonded Polyester Fabric by using Low-melting-point Bicomponent Filament Yarn - Head tie - (저융점 복합사에 의해 열융착된 폴리에스테르 직물의 염색 - 헤드타이를 중심으로 -)

  • Ji, Myeong-Gyo;Lee, Shin-Hee
    • 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.

Measurement Methods of Latent Heat for PCM with Low Melting Temperature in Closed Tube

  • Hong Hiki;Kang Chaedong;Peck Jong Hyeon
    • International Journal of Air-Conditioning and Refrigeration
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    • v.12 no.4
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    • pp.206-213
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    • 2004
  • Cycle test for developed phase change material (PCM) is necessary in order to assess the variation of latent heat, which decreases with time by deterioration. T-history method and measurement using heat-flux meter are appropriate for the cycle test in a tube filled with PCM because they do not need an extraction of sample in measuring heat of fusion. In the present study, these methods were applied to a PCM having a melting point below a room temperature, different to the past studies for PCMs melting above a room temperature. As a result of experiment using pure water as specimen, we can obtained rea-sonable values for heat of fusion.

Heat Transfer Characteristics of Micro-encapsulated Phase-Change-Material Slurry (잠열 마이크로캡슐 슬러리의 열전달 특성)

  • Kim, Myoung-Jun;Park, Ki-Won
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.6
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    • pp.518-525
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    • 2006
  • The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase-change material and water mixture slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration, heat flux, and the slurry velocity. The experimental results revealed that the increase of tube wall temperature of latent microcapsule slurry was lower than that of water caused by the heat absorption of fusion.

A Transient Modeling of Temperature Variation in a Melting Furnace of a Pyrolysis Melting Incinerator (열분해 용융소각로 내 용융로에서의 온도변화에 대한 과정론적 모델링)

  • Kim, Bong-Keun;Yang, Won;Yu, Tae-U
    • 한국연소학회:학술대회논문집
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    • 2006.04a
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    • pp.167-171
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    • 2006
  • The previous models for thermal behavior in the melting furnace were deterministic, composed of such a form that if the initial input conditions are determined, the results would have been come out by using the basic heat equilibrium equations. But making the experiment by trusting the analysis results, the melted slag is fortuitously set often, because temperature variation of the melted slag in the reaction process is not point function but path function. So in this study, a transient model was developed and verified by comparing with the experimental results.

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Measurement Methods of Latent Heat for PCM with Low Melting Temperature in Closed Tube (밀폐튜브 내 저온 PCM의 잠열측정법)

  • 류경용;박창현;백종현;홍회기
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.7
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    • pp.604-610
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    • 2003
  • Cycle test for developed phase change material (PCM) is necessary in order to analyze the variation of latent heat, which decreases with time by deterioration. 7-history method and measurement using heat flux meter are appropriate for the cycle test in a tube filled with PCM because they do not need an extraction of sample in measuring the heat of fusion. In the present study, these methods were applied to a PCM having a melting point below a room temperature, different from the past studies for PCMs melting above a room temperature. As a result of experiment using pure water as specimen, we can obtain reason-able values for heat of fusion by both methods.

High $T_c$ Superconductor Applications and Thick Film Preparation

  • Soh, Dea-Wha;Zhanguo Fan
    • Journal of information and communication convergence engineering
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    • v.1 no.2
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    • pp.63-66
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    • 2003
  • High $T_c$ superconducting lines will be applied as key materials in the areas of power transmission line; magnetic levitation of vehicle; magnetic separation; magnetic energy storage and marine propulsion. A combination method of electrophoresis deposition and zone-melting for preparation of YBaCuO tape is proposed. The submicron particle powder of YBaCuO made by sol-gel method is used in the electrophoresis process. A 40∼50 ${\mu}\textrm{m}$ thickness of YBaCuO film on Ag plate could be deposited in about three minutes. After deposition the film is rolled and heat treated in order to increase the density and the adhesion of the film to the Ag plate. Silver(Ag) and lead oxide(PbO) were added in the YBaCuO powder in order to reduce its melting point. The YBaCuO coating with controlled Ag and PbO contents was preliminarily zone-melted at about $945^{\circ}C$.

Preparation and Evaluation of Non-Crystalline Cefuroxime Axetil Solid Dispersion (비결정성 세푸록심 악세틸 고체분산체의 제조 및 평가)

  • Woo, Jong-Soo;Chang, Hee-Chul;Lee, Chang-Hyun
    • Journal of Pharmaceutical Investigation
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    • v.32 no.2
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    • pp.73-80
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    • 2002
  • Cefuroxime axetil is a cephalosporin antibiotic having a high activity against a wide spectrum of Grampositive and Gram-negative microorganisms. It is a cephalosporin antibiotic which exist as 2 diastereoisomers: diastereoisomer A and B. It shows polymorphism of three forms: a crystalline form having a melting point of about $180^{\circ}C$, a substantially amorphous form having a high melting point of about $135^{\circ}C$ and a substantially amorphous form having a low melting point of about 70^{\circ}C$. The crystalline form of cefuroxime axetil is slightly soluble in water because diastereoisomer A has lower solubility than B in water. Substantially amorphous form of which there are no difference in solubility between diastereoisomer A and B has better solubility than crystalline form, but it forms a thicker gel than crystalline form upon contact with an aqueous medium. Based on this reason, cefuroxime axetil is not readily absorbable in the gastrointestinal tract, rendering its bioavailability on oral administration very low. The object of this study was to develop an improved non-crystalline cefuroxime axetil composition having a high physicochemical stability and bioavailability. A non-crystalline cefuroxime axetil solid dispersant showing no peak on a Differential Scanning Calorimetry (DSC) scan is prepared by dissolving cefuroxime axetil and a surfactant in an organic solvent; suspending a water-insoluble inorganic carrier in the resulting solution; and spray drying the resulting suspension to remove the organic solvent, said solid dispersant having an enhanced dissolution and stability of cefuroxime axetil and being useful for the preparation of a pharmaceutical composition for oral administration. Tablet was formulated with this cefuroxime axetil solid dispersant, disintegrants and other ingredients. It disintegrated and dissolved easily and dynamically in dissolution medium, so showed a good dissolution profile.

Development of Automatic Filling Process using Low-Melting Point Metal for Rapid Manufacturing with Machining Process (절삭가공과 저융점금속에 의한 쾌속제작용 자동충진공정 개발)

  • Shin, Bo-Seong;Yang, Dong-Yeol;Choi, Du-Seon;Kim, Ki-Don;Lee, Eung-Suk;Je, Tae-Jin;Hwang, Kyeong-Hyeon
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.3
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    • pp.88-94
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    • 2002
  • Recently, the life cycle and the lead-time of a product are to be shortened in order to satisfy consumer's demand. It is thus important to reduce the time and cost in manufacturing trial products. Several technique have been developed and successfully commercialized in the market of RPM(Rapid Prototyping and Manufacturing). However, most commercial systems currently use resins or waxes as the raw materials. So, the limited mechanical strength for functional testing is regarded as an obstacle towards broader application of rapid prototyping techniques. To overcome these problems, high-speed machining technology is being investigated worldwide for rapid manufacturing and even for direct rapid tooling application. In this paper, some fundamental experiments and analyses are carried out to obtain the filling time, materials, method, and process parameters for HisRP(High-Speed RP) process. HisRP is a new RP process that is combined high-speed machining with automatic filling. In filling process, Bi58-Sn alloy is chosen as filling material because of the properties of low-melting point, low coefficient of thermal expansion and no harm to environment. Also the use of filling wire it if advantage since it needs simple and flexible mechanism. Then the rapid product, for example a skull, is manufactured for aluminum material by HisRP process with an automatic set-up device thor 4-faces machining.