• Title/Summary/Keyword: Drop morphology

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Effect of Dispersion of Silver Particles on the Electrical Conduction in Silver-Polymer Composites. (Silver-polyner 적합도전류물에서 은립자의 분석상태가 전기운도에 미치는 영향)

  • 김한성;김재호
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.37 no.1
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    • pp.55-62
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    • 1988
  • The variation of electrical resistivity of silver particle-filled polymers with the volume percent of silver particles was investigated. Also, the relationships between the surface tension of polymer and dispersion effect of silver particles were studied to find the steep drop of electrical resisivity, in view of agglomerate morphology. The critical volume precent of silver particles varied depending on the polymer species and increased with the increasing surface tension of polymer. The steep variation of resistivity with the increasing temperature was explained with the expansion of polymer at the melting temperature of polymer. The conductive break down current increased with the increasing volume percent of silver particles in the Ag/LDPE system and that was attributed to heat of Joule taken througn the contact area between the silver particle.

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Novel green Sr4ScAl3O10:Eu2+ phosphor prepared by the melt quenching technique

  • Toda, Kenji;Iwaki, Masato;Katsu, Minenori;Kamei, Shin-nosuke;Kim, Sun-Woog;Hasegawa, Takuya;Muto, Masaru;Yamanashi, Ryota;Sakamoto, Tatsuya;Ishigaki, Tadashi;Uematsu, Kazuyoshi;Sato, Mineo;Yoon, Dae-Ho
    • Journal of Ceramic Processing Research
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    • v.20 no.3
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    • pp.276-279
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    • 2019
  • New green-emitting Sr4ScAl3O10:Eu2+ phosphor was prepared using a novel melt quenching synthesis method. The temperature of raw materials irradiated with the strong light of the Xe arc-lamp was rose up to about 2273 K, followed by a sharp drop in the temperature after turn off the lamp. This method is a useful tool for rapid screening of novel phosphor materials.

Effect of Reflow Number and Surface Finish on the High Speed Shear Properties of Sn-Ag-Cu Lead-free Solder Bump (리플로우 횟수와 표면처리에 따른 Sn-Ag-Cu계 무연 솔더 범프의 고속전단 특성평가)

  • Jang, Im-Nam;Park, Jai-Hyun;Ahn, Yong-Sik
    • Journal of the Microelectronics and Packaging Society
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    • v.16 no.3
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    • pp.11-17
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    • 2009
  • The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

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Accumulation of Lipid Including Cholesterol in Murine Hepatocytes with Hyperlipidemia Induced by Triton WR-1339 (Triton WR-1339 주사에 의한 고지혈증 유발시 간세포내 지방 축적에 관한 형태학적 연구)

  • Park, In-Sick;Ahn, Sang-Hyun;Kim, Jin-Taek
    • The Journal of Dong Guk Oriental Medicine
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    • v.6 no.1
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    • pp.107-115
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    • 1997
  • Hapatic tissues of ICR mouse intraperitoneally injected with Triton WR-1339 were observed to investigate the morphologic change of liver by destruction of lipid metabolism as hyperlipidemia. The hepatic tissues were obtained at hour-24, 48, and 72 after triton injection that were fixed in fromol-calcium solution and were cryocut. These tissues were stained by H&E for general morphology, sudan black B for lipid, and perchloric acid-naphthoquinone method for cholesterol. The increase of hepatocyte having meshlike cytoplasm were shown in all hepatic lobules after triton injection and the hepatic plates were disappeared in the region aggregated meshlike hepatocyte. The number of blue black colored lipid drop and dark green colored asterisk shaped cholesterol particle in hepatic cytoplasm were increased than the saline injected mouse and the size of lipid drop was enlarged. As results indicated that the lipid metabolism were destructed by triton injection, subsequently hepatocyes accumulated with lipid including cholesterol.

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Development of Lamella Morphology in Poly(ethylene terephthalate)/Polycarbonate Blends

  • Lee, Jong-Kwan;Im, Jeong-Eon;Lee, Kwang-Hee
    • Macromolecular Research
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    • v.12 no.2
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    • pp.172-177
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    • 2004
  • We have studied the lamella-level morphology of poly(ethylene terephthalate) (PET)/polycarbonate (PC) blends using small-angle X-ray scattering (SAXS). Measurements were made as a function of the holding time in the melt. We determined the morphological parameters at the lamellar level by correlation function analysis of the SAXS data. An increased amorphous layer thickness was identified in the blend, indicating that some PC was incorporated into the interlamellar regions of PET during crystallization. The blend also exhibits a larger lamella crystalline thickness (l$\sub$c/) than that of pure PET. A possible reason for the increase in l$\sub$c/ is that the inclusion of the PC molecules in the interlamellar regions causes an increase in the surface free energy of folding. At the early stage of isothermal crystallization, we observed a rapid drop in the value of l$\sub$c/ in the blend; this finding indicates that a relatively large fraction of secondary crystals form during the primary crystallization. In contrast, the value of l$\sub$c/ for the sample that underwent a prolonged holding time increased with time in the secondary crystallization-dominant regime; this observation suggests that the disruption of chain periodicity, which results from transesterification between the two polymers, favors the development of fringed micellar crystals that have larger values of l$\sub$c/ rather than the development of normal chain-folded crystals.

Change of Surface Morphology with the Spreading Rate of Organic Solution During Interfacial Polymerization for Polyamide-based Thin Film Composite Membrane Manufacturing Process (폴리아마이드계 박막복합막 제조 공정에서 계면중합의 유기용액 퍼짐 속도에 따른 표면 모폴로지의 변화)

  • Park, Chul Ho
    • Membrane Journal
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    • v.27 no.6
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    • pp.506-510
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    • 2017
  • The interfacial polymerization method has been applied to various fields as a reaction in which reactive monomers dissolved in two immiscible solutions cause polymerization at the interface. In the case of water treatment membranes, m-phenylene diamine and trimesoyl chloride are used as reactants. The performance of the membrane is affected by various polymerization factors. In this study, we investigated how the spreading rate of the organic solution influences the surface and structure of the membrane. Spreading rate of organic solutions was adjusted to 7.6 and 25 mm/sec. The solution volume of the organic phase was adjusted to 1~3 drops. The observed results showed that cracks were not found in the polyamide membrane when dropping at a drop of 7.6 mm/sec and dropping two drops at 25 mm/sec. On the other hand, cracks occurred in all cases. Therefore, the spreading rate of the initial organic solvent is expected to greatly affect the performance of the polyamide membrane.

A Study on the Extrusion Foaming of Polypropylene (폴리프로필렌의 압출발포 특성에 관한 연구)

  • 황대영;한갑동;홍다윗;이규일;이기윤
    • Polymer(Korea)
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    • v.24 no.4
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    • pp.538-544
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    • 2000
  • The characteristics of cell growth and foamed cell structures of PP were investigated by a continuous foaming process. The operating parameters were the contents of blowing agent and nucleating agent, nucleating agent contents, die temperatures and die dimensions. The foaming cells grew without collapse at less than 14.5 wt% of blowing agent, isopentane. But the cells were collapsed when the blowing agent content was more than 14.5 wt%. The foam density dramatically decreased when a very small amount of the nucleating agent, 1 wt%, was added. After the nucleating agent was added, the cell's weight plummeted to one-seventh of its previous weight. Stable foam cell structures were formed at the die temperature of 17$0^{\circ}C$. However, the effects of the pressure drop rate on the cell morphology were not serious.

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The Effect of Microstructure and Temperature on Fatigue Crack Propagation in Ti-3A1-2.5V A11oy (Ti-3A1-2.5V 합금의 피로균열전파특성에 미치는 미세조직 및 온도의 영향)

  • 임병수
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.2
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    • pp.58-66
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    • 1997
  • Ti alloys, with the advantageous tensile strength/density ratio and the chemical stability, have been used widely in the aerospace and chemical engineering industries and their usages are still expanding in various industrial areas. In the automotive industry, because of their superior merits of weight reduction and fuel saving, Ti alloys are expected to be used as various part materials including connecting rods, engine valves, springs and retainers, which are all subjected to the fatigue loads. In this study, using Ti-3A1-2.5V, the effects of temperature and microstructure change on fatigue crack propagation has been investigated. Five different microstructures were tested at the temperatures of room temperature, 20$0^{\circ}C$, 30$0^{\circ}C$ and 40$0^{\circ}C$ under the same frequency 20Hz. Some of the conclusions obtained are as follows: (1)Microstructurally, the morphology of less $\alpha$-phase and finer lamellar structure of $\alpha$ and $\beta$-Ti showed better registance to the fatigue crack propagation. (2)Fatigue crack growth rate increased with test temperature.

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Development of Metal Filter with Nanoporous Structure by Adhesion of Metal Nanoparticles Sintered onto a Micor-Filter (마이크로-필터 상에 소결 처리된 금속 나노입자 고착에 의한 나노기공체 금속 필터 개발)

  • Lee, Dong Geun;Park, Seok Joo;Park, Young Ok;Ryu, Jeong In
    • Korean Chemical Engineering Research
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    • v.46 no.2
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    • pp.397-401
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    • 2008
  • The nanoparticle-agglomerates are synthesized by laser ablation, which have the morphology of dendrite structure. The filtration performance of a conventional micron-fibrous metal filter was improved by adhering nanoparticle-agglomerates onto the filter surface. The Sintered-Nanoparticle-Agglomerates-adhered Filter (SNAF) adhered with nanostructured material was made by heat treatment after deposition of nanoparticle-agglomerates sintered in aerosol phase onto the micron-fibrous metal filter. As the sintering temperature increases, the pressure drop of the filter increases a little but the filtration efficiency increases remarkably. This is due to increase of surface area of nanoparticle-agglomerates adhered onto the micron-fibrous metal filter.

Physical Properties of Human Hair by the Bleach (탈색시술 조건에 따른 모발의 물성변화)

  • Yun, Jong-Hyun;Kim, Ho-Jung;Lee, Young-Joo;Park, Cha-Cheol
    • Fashion & Textile Research Journal
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    • v.7 no.1
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    • pp.96-100
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    • 2005
  • The bleaching is one of the worst factors which leads to the damage of the human hair. The cuticle of the human hair is injured by the alkali that is one of the chief ingredients of a bleaching agent. The alkali component of the bleaching solution chemically reacts with human hair, reducing the tenacity and dissolving the cuticle layer. The purpose of this study is to examine the effects of bleaching time and temperature on the physical properties and morphology. The results were as follows. 1. The stress-strain curves for human hair indicated the three distinct regions, such as Hookean region, Yield region and post-Yield region. The tenacity of hair is reduced gradually with an increase of bleaching time. Under these same conditions, elongation of the hair increased. 2. The greatest drop in tenacity for hair occured between $40^{\circ}C$ and $60^{\circ}C$ of bleaching temperature. 3. Compared with the virgin hair, bleached hair showed a slower rate of weight reduction in the TGA thermogram. The rate decreased gradually as the bleaching time and temperature increased. 4. As the bleaching conditions reached time and temperature extremes, the human hair cuticle became more damaged. The cuticle layers seemed to have dissolved, as seen in the SEM photographs.