• Title, Summary, Keyword: phase behavior

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Phase Behavior of Binary and Ternary Blends Having the Same Chemical Components and Compositions

  • Yoo, Joung-Eun;Kim, Yong;Kim, Chang-Keun;Lee, Jae-Wook
    • Macromolecular Research
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    • v.11 no.5
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    • pp.303-310
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    • 2003
  • The phase behavior of binary blends of dimethylpolycarbonate-tetramethyl polycarbonate (DMPCTMPC) copolycarbonates and styrene-acrylonitrile (SAN) copolymers has been examined and then compared with that of DMPC/TMPC/SAN ternary blends having the same chemical components and compositions except that the DMPC and TMPC were present in the form of homopolymers. Both binary and ternary blends were miscible at certain blends compositions, and the miscible blends showed the LCST-type phase behavior or did not phase separated until thermal degradation temperature. The miscible region of binary blends is wider than that of the corresponding ternary blends. Furthermore, the phase-separation temperatures of miscible binary blends are higher than those of miscible ternary blends at the same chemical compositions. To explain the destabilization of polymer mixture with the increase of the number of component, interaction energies of binary pairs involved in these blends were calculated from the phase separation temperatures using lattice-fluid theory and then the phase stability conditions for the polymer mixture was analyzed with volume fluctuation thermodynamics.

Effect of Liquid Crystal Structures on olymerization-induced Phase Separation Behavior by Simultaneous Resistivity and Turbidity Measurement

  • Park, Su-Cheol;Lee, Sang-Sub;Hong, Jin-Who
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.886-889
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    • 2007
  • Photopolymerization and phase separation behavior during the PDLC formation process were investigated by simultaneous resistivity and turbidity measurement. Using this experimental method, we investigated the effect of liquid crystal structure on photopolymerization and phase separation behavior.

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Effects of Competition between Phase Separation and Ester Interchange Reactions on the Phase Behavior in a Phase-Separated Immiscible Polyester Blend: Monte Carlo Simulation

  • Youk, Ji-Ho;Jo, Won-Ho
    • 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.

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The Theoretical and Experimental Value on the Stress-Strain Behavior of Dual Phase Steels (복합조직강의 응력-변형 거동에 관한 이론치와 실험치)

  • 오택열;김석환;유용석
    • Journal of the Korean institute of surface engineering
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    • v.26 no.2
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    • pp.63-70
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    • 1993
  • The mechanical properties of ferrite-martensited dual phases steels are affected by the microstructural factors, such as martensited volume fractions, ferrite grain size, strength ratio, connectivity, etc. Two phase alloys are technologically important. However, there is a lack of understanding as to stress-strain behavior of dual phase alloy in terms of stress-strain behavior of each component phases. The lack of the understanding stems from the complex deformation behavior of two phase alloys. The aim of this study is to rationalize stress-strain behavior of dual phase alloy in terms of the stress-strain behavior of component phase by systematically considering all the factors listed above. It was found that for a given martensite volume fraction, the calculated stress-strain curve was higher for a finer particles size than for a coarse particle sized within the range of the strains considered, and this behavior was seen for all the different volume fraction alloys considered. The calculated stress-strain curves were compared with corresponding experimental curves, and in general, good agreement was found. The maximum difference in flow stress between the calculated and the experimental results occurs at the nearly beginning of the plastic deformation.

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The Effects of Intramolecular Interactions of Random Copolymers on the Phase Behavior of Polymer Mixtures

  • Kim, M. J.;J. E. Yoo;Park, H. K.;Kim, C. K.
    • Macromolecular Research
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    • v.10 no.2
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    • pp.91-96
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    • 2002
  • To explore the effects of intramolecular interactions within the copolymer on the phase separation behavior of polymer blends, copolymers having two different types of intramolecular interactions, i.e., intramolecular repulsion and intramolecular attraction were prepared . In this study, poly(styrene-co-methylmethacrylate) (P(S-MMA)) having intramolecular repulsion caused by positive interaction between styrene and MMA and poly(styrene-co-ethyl-methacrylate) (P(S-EMA)) and poly(styrene-co-cyclohexylmethacrylate) (P(S-CHMA)) having intramolecular attraction caused by negative interaction between styrene and methacrylate were blended with tetramethyl poly-carbonate (TMPC). The phase behavior of blends was examined as a function of copolymer composition and blend composition. TMPC formed miscible blends with styrenic copolymers containing less than certain amount of methacrylate. The phase separation temperature of TMPC blends with copolymer such as P(S-MMA) and P(S-EMA), first increases with methacrylate content, goes through a maximum and then decreases just prior to the limiting content of methacrylate for miscibility, while that of TMPC blends with P(S-CHMA) always decreases. The calculated interaction energy for TMPC-P(S-EMA) pair is negative and monotonically increases with EMA content of the copolymer. Such behavior contradicted the general notion that systems with more favorable energetic interactions have higher LCST, The detailed inspection of the lattice-fluid theory related to the phase behavior was performed to explain such behavior.

High temperature deformation behavior of $\alpha\;and\;\beta$ phase of Ti-6Al-4V alloy with an equiaxed microstructure (등축정 Ti-6Al-4V 합금의 $\alpha,\;\beta$ 구성상의 고온변형거동 규명)

  • Lee, You-Hwan;Yeom, Jong-Taek;Park, Nho-Kwang;Lee, Chong-Soo;Kim, Jeoung-Han
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.295-298
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    • 2005
  • High temperature deformation behavior of $\alpha\;and\;\beta$ phase of Ti-6Al-4V was investigated within the framework of a self-consistent approach at various temperature ranges. To examine the flow behavior of u-phase, Ti-7.0Al-1.5V alloy was used, whose chemical composition is close to that of the $\alpha$ phase in Ti-6Al-4V at hot working temperatures. The flow stress of $\beta$ phase was predicted by using self-consistent approach. The flow stress of $\alpha$ phase was higher than that of $\beta$ phase above $750^{\circ}C$, while the $\beta$ phase revealed higher flow stress than a phase at $650^{\circ}C$. It was found that the relative strength and strain rate ratio between $\alpha\;and\;\beta$ phase significantly varied with temperature. From this approach, the mode for grain matrix deformation was proposed as a mixed type of both iso-stress and iso-strain rate modes.

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Associations between Eating Behavior and the Eating Patterns of Female College Students Across the Menstrual Cycle (여대생의 월경주기에 따른 섭식패턴과 섭식행동의 관련성)

  • Kim, Seok-Young
    • Korean Journal of Community Nutrition
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    • v.21 no.5
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    • pp.405-414
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    • 2016
  • Objectives: The associations between the eating behavior and energy and macronutrient intake from meals and snacks consumed during different times of the day across the menstrual cycle were investigated in 74 healthy female college students. Methods: A 9-day food record was collected during the last 3 days before menstrual onset (phase 1) and the first 3 days after menstrual onset (phase 2) and from the 4th to the 6th day after menstrual onset (phase 3), respectively. Anthropometry was assessed and eating behaviors were measured using the Dutch Eating Behavior Questionnaire (DEBQ). Results: External eating was the most prevalent type of eating behavior, followed by restrained eating and emotional eating. Restrained eating was positively associated with energy, carbohydrate and lipid intake at the breakfast and midmorning snack during phase 3. However, emotional eating was also positively related to energy and macronutrient intake at the dinner and after-dinner snack during phase 1 and phase 3, with higher level detected in the phase 1. The association of emotional eating with the snack consumption was highest in phase 1. External eating was positively associated with energy and macronutrient intakes at the dinner and after-dinner snack across the three phases, the highest level being phase 1. In addition, restrained eating was positively associated with the weight, body mass index(BMI), fat mass, waist and hip girth of the subjects. Conclusions: Eating behaviors varied with regard to meals and snacks consumed during different times of the day across the three menstrual phases. Dinner and afterdinner snack consumption in premenstrual phase could be considered as a time when women are more prone to overconsumption and uncontrolled eating.

The Effect of Bee Venom Acupuncture into Chok-samni (ST 36) Formalin-induced Pain Behavior (족삼리(足三里) 봉독약침자극(蜂毒藥鍼刺戟)이 Formalin-induced Pain Behavior 에 미치는 영향(影響))

  • Yim, Yun-Kyoung;Seo, Jung-Chul;Kim, Yong-Suk;Kim, Chang-Hwan;Lee, Yun-Ho;Choi, Do-Young
    • Journal of Acupuncture Research
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    • v.17 no.2
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    • pp.139-152
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    • 2000
  • This study was designed to evaluate the analgesic effect of bee venom (BV) Acupuncture into different treatment points, Chok-samni (ST36) and blank loci of the gluteal muscle and back. We investigated the changes in formalin-induced pain behavior according to the pretreatment with different concentrations of BV, thirty minutes before the formalin injection. The results were summarized as follows: 1. The formalin-induced pain behavior was suppressed by pretreatment with BV into Chok-samni (ST36) in a dose dependent manner. During the early phase, 0.08mg/kg of BV showed a statistically significant suppression in the formalin-induced pain behavior. Moreover, 0.008mg/kg, 0.016mg/kg, and 0.08mg/kg of BV, except 0.0016mh/kg of BV, had significant suppresive effects on the formalin-induced pain behavior during the late phase. Therefore, these data indicated that the suppressive effect of BV acupuncture on the formalin-induced pain behavior was stronger in the late phase rather than the early phase 2. In order to investigate the analgesic effect of BV acupuncture into different treatment points, the experimental animals were divided into three groups: Chok-samni (ST36) group, gluteal group and back group. In the Chok-samni (ST36) group, the formalin-induced pain behavior during all the phases was significantly reduced as compared with that of the back group. However, as compared with that of the gluteal group, the formalin-induced pain behavior in the Chok-samni (ST36) group was decreased only in the late phase, not in the early phase. The formalin-induced pain behavior in the gluteal group was significantly reduced as compared with that of the back group in the late phase, not in the early phase. We suggested that the analgesic effect of BV acupuncture into Chok-samni (ST36) was most effective among Chok-samni (ST36), gluteal, and the back groups in formalin-induced pain behavior.

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An Interdisciplinary Case Study on the Phase-Shifting Behavior of Financial Markets (자본시장의 위상전이행태에 관한 학제간 융합연구 : 사례연구)

  • Ryu, Doojin;Ju, Kangjin;Kim, Hyun Na;Yang, Heejin
    • Korean Management Science Review
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    • v.33 no.2
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    • pp.117-131
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    • 2016
  • This study introduces the concepts on the phase-shifting phenomenon of financial markets, which was firstly used in econophysics area and explains how the phase-shifting behavior is studied in the fields of business management and finance. Specifically, we explain how the phases of financial markets are extremely changed under some external conditions, do an extensive literature review, and carry out case studies focusing on the 3 major financial crisis events including the 87 October crash, 97 Asian financial crisis, and 2007 global financial crisis. We also empirically examine the phase-shifting behavior of the Korean ELW products that has a similar payoff structure to the KOSPI200 options.

TCC behavior of a shell phase in core/shell structure formed in Y-doped BaTiO3: an individual observation (Yttrium이 첨가된 BaTiO3에서 형성된 core/shell 구조에서 shell의 TCC 거동: 독립적 관찰)

  • Jeon, Sang-Chae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.30 no.3
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    • pp.110-116
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    • 2020
  • Grains in the BaTiO3, which is used for a dielectric layer in MLCC(Multi-Layer Ceramic Capacitor) are necessary to form core/shell structure for a stable TCC(Temperature Coefficient of Capacitance) behavior. The shell property has been deduced from the whole TCC behavior of core/shell structure due to its tiny size, ~ few ㎛. This study demonstrates the individual TCC behavior of the shell phase measured by micro-contact measurement in a temperature range between 35 and 135℃. Pt electrode pairs deposited on an enlarged core/shell structure in a diffusion couple sample made the measurement possible. As a result, the DPT (Diffusion Phase Transition) behavior of the shell phase was revealed as a different TCC behavior from that of the core: a broad peak with Tm at 65℃. This would be also useful experimental data for a modelling that depicts dielectric-temperature behavior of core/shell structure.