• Title/Summary/Keyword: Melting point

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Fundamental study on development of latent heat storage material for waste heat recovery of biomass gasification

  • Kim, MyoungJun;Yu, JikSu;Chea, GyuHoon
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.5
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    • pp.533-540
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    • 2014
  • Recently, latent heat thermal energy storage system (LHTES) has gained attention in order to utilize middle temperature (373~573 K) waste heat from biomass gasification. This paper has investigated thermo-physical properties of erythritol [$CH_2OHCHOH$ $CHOHCH_2OH$], mannitol [$CH_2OH$ $(CHOH)_4CH_2OH$] and their compounds as phase change materials (PCMs). The differential scanning calorimetry (DSC) was applied to measure the melting point and latent heat of these PCMs. Also the melting and solidification characteristics of these PCMs were observed in a glass tube with a digital camera. In the DSC measurement, when the amount of mannitol content was more than 40 mass%, the melting point of these compounds show two melting points. The experimental results showed that the velocity of melting and solidification were different for every mixture ratio of compounds. These compounds had the super-cooling phenomenon during the solidification process.

A Study on melting and bridge phenomena of solder paste (Solder paste의 용융 및 bridge현상 관찰연구)

  • 안병용;정재필
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.442-446
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    • 1999
  • Melting behavior and bridge phenomenon of solder paste, which is essential for surface mount technology in packaging, were investigated. solder paste of Sn-37%Pb was printed on Sn-coated Cu-pattern of PCB, and heated over melting point. Melting behavior of the paste was observed using CCD-camera. In order to modelize the melting and agglomeration phenomena of the paste, two solder balls of 0.76mm diameter were used. As experimental results, the paste start to melt from the margin of the printed shape. The hight of the melted paste decreased from 270 $\mu$m to 200 $\mu$m firstly, and finally recovered to 250 $\mu$m. During the melting procedure, pores were evolved from the molten paste. Bridge Phenomenon of the molten Paste depends upon the pitch of the pattern.

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The Effect of Electromagnetic Stirring on the Semi-Solid Microstructure of Cu-0.15wt%Zr Alloy (전자교반에 의한 Cu-0.5wt%Zr 합금의 반응고 조직제어에 관한 연구)

  • Lim, Sung-Chul;Lee, Heung-Bok;Kim, Kyung-Hoon;Kwon, Hyuk-Chon;Yoon, Eui-Pak
    • Journal of Korea Foundry Society
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    • v.26 no.1
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    • pp.40-45
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    • 2006
  • Most of the work reported concerned the semi-solid processing of low melting point alloys, and in particular light alloys of aluminum and magnesium. The purpose of this paper is to develop a semi-solid microstructure of Cu alloys using electromagnetic stirring applicable for squirrel cage rotor of induction motor. The size of primary solid particle and the degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were observed. By applying electromagnetic stirring, primary solid particles became finer and rounder relative to as-cast sample. As the input frequency increased from 30 to 40 Hz, particle size decreased. The size of primary solid particle was found to be decreased with increasing cooling rate. Also, it decreased with stirring up to 3 minutes but increased above that point. The degree of sphericity became closer to be 1 with hold time. Semi-solid microstructure of Cu alloys, one of the high melting point alloys, could be controlled by electromagnetic stirring.

Comparison of Hydrolysis from In Vitro Digestion Using Symmetric and Asymmetric Triacylglycerol Compounds by Enzymatic Interesterification (효소적으로 합성된 대칭형과 비대칭형 Triacylglycerol 혼합물의 In Vitro Digestion에서의 소화율 비교)

  • Woo, Jeong Min;Lee, Ki Teak
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.6
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    • pp.842-853
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    • 2014
  • For developing indigestible lipids, symmetric triacylglycerol (ST) and asymmetric triacylglycerol (AT) were produced by enzymatic interesterification using high oleic sunflower oil, palmitic ethyl ester, and stearic ethyl ester in a shaking water bath. Used enzymes were Lipozyme RMIM for ST and Lipozyme TLIM for AT. To remove ethyl ester from reactants, methanol fractionation (reactant : methanol=1:5, w/v, $25^{\circ}C$) and florisil separation (reactant : florisil=1:8, w/w) were applied. Acetone fractionation (reactant : acetone=1:9, w/v) was implemented to separate triacylglcerol (TAG) species into ST and AT. Fractions I (before fractionation), II (after fractionation, liquid phase) and III (after fractionation, solid phase) were separated from ST, whereas fractions IV (after 1st fractionation, liquid phase) and V (after 2nd fractionation, solid phase) were from AT. From sn-2 fatty acid composition analysis, the sum of palmitic acid (C16:0) and stearic acid (C18:0) was 4.9~6.5 area% in ST (I, II, III), and 41.9~43.9 area% in AT (IV, V). In vitro digestion was performed for 0, 15, 30, 60, and 120 minutes at $37^{\circ}C$ in a shaking water bath. For the digestion results, hydrolysis of V was only 40% compared to others (I, II, III, IV) at 120 minutes due to its melting point ($49^{\circ}C$). However, initially (15 minutes), hydrolysis (%) was as follows: V$32.5^{\circ}C$, $31.8^{\circ}C$) and different slip melting points ($31.3^{\circ}C$, $19.5^{\circ}C$). Even though IV has a lower TAG content composed of two saturated fatty acids than III, it had a similar melting point.

Preparation of Thermal Bonding Fabric by using-low-melting-point Bicomponent Filament Yarn - Head tie - (저융점 복합사를 이용한 열융착 직물의 제조(I) - 헤드타이를 중심으로 -)

  • Ji, Myeong-Kyo;Lee, Shin-Hee
    • Fashion & Textile Research Journal
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    • v.11 no.3
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    • pp.474-480
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    • 2009
  • The purpose of this study is to prepare the hardness 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 were composed with a regular PET core and low melting PET sheath. The thermal bonding of PET fabric was carried out in pin tenter from 120 to $195^{\circ}C$ temperature range for 60 seconds. In this study, we investigated the physical properties and melting behavior of PET fiber and the effect of the temperature of the pin tenter on the thermal bonding, mechanical properties. Melting peak of warp showed the thermal behavior of general PET fiber. However, melting peak of weft fiber(bicomponent fiber) showed the double melting peak. The thermal bonding of the PET fabric formed at about temperature of lower melting peak. The optimum thermal bonding conditions for PET fabrics was applied at $190{\sim}195^{\circ}C$ for 60seconds by pin tenter. On the other hand, the tensile strength of the PET fabric decreased with an increasing temperature of thermal bonding.

Precise Temperature Control by Locking on the Fixed point of Gallium (갈륨의 고정점을 이용한 정밀 온도제어)

  • 김태호;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.351-354
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    • 2002
  • The new enhanced method of temperature control need not any reference temperature, the system itself can find the melting temperature of gallium as a reference point by dithering input heat flux. If gallium is in melting state, the latent heat of fusion works, so gallium temperature does not change on dithering input heat flux. Also, the control method can determine the state of gallium; solid, liquid, or melting state by investigating the temperature in gallium. We apply this new temperature stabilization method to stabilize a Fabry-Perot cavity, which serves as a ultimate length measurement technique. We achieved 1 mK-temperature stability and 1.5426 nm/ 95 mm-length stability over 10 hours.

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Miscibility and Properties of cis-Polybutadiene/Ethyl-Branched Polyethylene Blends (II)

  • Cho, Ur-Ryong
    • Macromolecular Research
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    • v.8 no.2
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    • pp.66-72
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    • 2000
  • Cis-Polybutadiene (cis-PBD) and the three polyethylenes (PE's) having different branch content were mixed to investigate crystallinity, thermodynamic interaction parameter(c), and diluents effect. Crys-tallinty of PE's decreased with increasing content of amorphous cis-PBD because of a decrease in both the degree of annealing and kinetics of diffusion of the crystallizable polymer content. The thermodynamic interaction parameter(c) for the three blend systems approximately equals to zero near the melting point. These systems were determined to be miscible on a molecular scale near or above the crystalline melting point of the crystalline PE's. From the measurement of T$\sub$m/ vs. T$\sub$c/ behavior, all the three blends showed a straight line for a plot of T$\sub$m/ vs. T$\sub$c/. This result means that the melting behavior of PE is mainly due to a diluent effect of cis-PBD component.

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Manufacture of Soluble Micro-fiber and Low Melting Polymer for Interior Synthetic Leather (인테리어용 인조가죽을 위한 용출형 극세사와 저온 융착사의 제조)

  • Ahn, Young-Moo
    • Korean Journal of Human Ecology
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    • v.12 no.4
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    • pp.529-537
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    • 2003
  • This study was conducted to manufacture the soluble micro-fiber and to synthesize low melting polymer for the interior fabric not to use the polyurethane resin causing some problems. Low melting polyester for weft yarn was introduced by adding 30-40 mol% ratio of isophthalic acid to a main chain of polyethylene terephthalate to decrease the melting temperature up to heat setting temperature. Micro-fiber for warp yarn consisted of both soluble and insoluble components with multi-layered structure. When the soluble micro-fiber was treated by alkaline hydrolysis with 3-5% concentration of NaOH, it showed the turning point at 28% weight loss since soluble polyester was hydrolyzed approximate five times faster than regular polyester.

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Seed melting during seeded-melt growth process of YBCO superconductors

  • Kim, Chan-Joong;Hong, Gye-Won;Kim, Ho-Jin
    • 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.

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The Thermal conductivity analysis and performance evaluation on the pavement applying geothermal snow melting system (지열 융설시스템을 적용한 포장체의 열전도분석 및 구조안전성 검토)

  • Lee, Seung-Ha;Park, Jeong-Sik;Lee, Seok-Jin;Kim, Bong-Chan
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.6 no.1
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    • pp.17-22
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    • 2010
  • A sliding accident on the road have a high percentage by road freezing, especially, it is often appeared at bridges and tunnel of freezing areas. Thus, the stability of road operations is enhanced by preventing a partial freezing phenomenon. According to the geothermal snow melting system analysis, a pattern of thermal conductivity is found out about pavement materials of concrete and asphalt when it is buried. For the feasibility study on geothermal snow melting system, analysis of the ground melting point when operating system, life evaluation of pavements and safety evaluation of pipes are performed.