• 제목/요약/키워드: Avrami Equation

검색결과 73건 처리시간 0.023초

차생엽을 첨가한 인절미의 저장중 노화에 미치는 영향 (Effects on retrogradation of Injeulmi(Korean glutinous rice cake) added with the macerated tea leaves during storage)

  • 이미경;김성수;이상효;오상룡;이성우
    • Applied Biological Chemistry
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    • 제33권4호
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    • pp.277-281
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    • 1990
  • 차생엽을 첨가한 인절미 제조시험 결과 텍스쳐에서 경도, 탄성, 응집성, 씹힘성, 검성은 첨가량이 증가할수록 대체로 감소하여 차생엽에 의한 인절미의 치밀하고 쫄깃한 조직감이 약 간 부드럽게 변하였다. 관능검사 결과 색깔은 5% 첨가구가 엷은 녹색을 띠며, 5% 유의수준에서 가장 양호하였으며, 향은 10% 첨가구가 5% 유의수준에서 가장 좋았고, 조직감은 첨가구별 유의차는 없었으며 전체적인 관능품질은 5%와 10% 첨가구가 무첨가구와 15% 첨가구에 비하여 1% 유의수준에서 좋게 평가되었다. 저장기간중 인절미의 경도 변화는 차생엽 10% 첨가구가 무첨가구에 비하여 낮은 증가율을 보여 주었으며, Avrami 지수와 노화속도 상수를 구한 결과 무첨가구가 각각 1.062와 15.3인데 비하여 10% 첨가구는 0.989와 41.6으로 차생엽 첨가에 의하여 노화가 지연되는 것으로 나타났다.

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Phase Intergrowth in the Syntheses of BSCCO Thin Films

  • Park, No-Bong;Park, Yong-Pil
    • 한국전기전자재료학회논문지
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    • 제15권8호
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    • pp.736-741
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    • 2002
  • Phase intergrowth some kinds of the $Bi_2Sr_2Ca_{n-1}Cu_nO_y$ phases is observed in the thin film fabrication at ultralow co-deposition with multi targets by means of ion beam sputtering. The molar fraction of the Bi2212 phase in the mixed crystal of the grown films is investigated as a function of the applied ozone pressure and the substrate temperature. The activation energy for the phase transformation from the Bi2201 to the Bi2212 is estimated in terms of the Avrami equation. This study reveals that the formation of a liquid phase contributes significantly to the construction of the Bi2212 phase in the thin films, differing from the bulk synthesis.

Phase Intergrowth in the Syntheses of Bi-superconducting Thin Films

  • Chun, Min-Woo;An, In-Soon;Park, Yong-Pil
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 하계학술대회 논문집
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    • pp.490-493
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    • 2002
  • Phase intergrowth some kinds of the Bi$_2$Sr$_2$Ca$\_$n-1/Cu$\_$n/O$\_$y/ phases is observed in the thin film fabrication at ultralow co-deposition with multi targets by means of ion beam sputtering. The molar fraction of the Bi2212 phase in the mixed crystal of the grown films is investigated as a function of the applied ozone pressure and the substrate temperature. The activation energy for the phase transformation from the Bi2201 to the Bi2212 is estimated in terms of the Avrami equation. This study reveals that the formation of a liquid phase contributes significantly to the construction of the Bi2212 phase in the thin films, differing from the bulk synthesis.

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Seed 입자 첨가에 따른 $BaTiO_3$ 요업체의 비정상 입성장거동 (Abnormal Grain Growth Behavior of $BaTiO_3$ Ceramics with Addition of Seed Grains)

  • 이태헌;김정주;김남경;조상희
    • 한국세라믹학회지
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    • 제32권5호
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    • pp.587-593
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    • 1995
  • Abnomal grain growth behavior of BaTiO3 ceramics was investigated with addition of seed grains. It was foudn that the nucleation rate of abnormal grain was constant and growth of abnormal grain was linearly increased with sitnering time, regardless of amount of seed grains. These facts were also confirmed by fitting of the volume fraction of abnormal grain vs. sintering time using Avrami type equation (n=4). It was suggested that seed grains did not change the nucleation rate or growth mechanism of abnormal grain but increase the number of abnormal grains at initial stage of sintering and then it led to fine microstructure of BaTiO3 ceramics.

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폴리프로필렌/옥수수전분 블렌드의 비등온결정화 거동 연구 (Study on the Non-isothermal Crystallization Behavior of Polypropylene/Corn Starch-MB Blends)

  • 김연철
    • 한국산학기술학회논문지
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    • 제9권5호
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    • pp.1125-1129
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    • 2008
  • 폴리프로필렌(polypropylene, PP)/옥수수전분(corn starch) 마스터뱃취(MB)(전분 MB) 블렌드를 PP 함량을 90, 80, 70, 60 wt%로 변화시키며 실험실 규모의 Brabender mixer를 이용하여 $200^{\circ}C$에서 제조하였다. PP/전분MB 블렌드의 화학구조, 기초 열적특성 및 비등온결정화거동을 적외선분광기 (FT-IR), 시차주사열용량분석기(DSC) 그리고 열중량분석기(TGA)를 이용하여 관찰하였다. PP/전분MB 블렌드의 제조는 수산기의 존재여부를 통해 확인하였다. 용융온도 및 엔탈피에는 큰 변화가 나타나지 않음을 알 수 있었고, 블렌드의 분해온도는 전분MB 함량에 따라 감소하고 있음을 보여주었다. PP/전분MB 블렌드의 비등온결정화 거동은 Avrami 방정식을 이용하여 분석하였다. Avrami 지수의 경우 PP는 2.71-3.97의 값을 나타내었고, PP/전분MB 블렌드의 경우는 1.48-1.99 값을 보여주었다. 활성화에너지는 Kissinger 방법에 의해서 계산되었고, PP의 경우 233 kJ/mol, PP90은 484 kJ/mol, PP80은 541 kJ/mol, PP70은 553 kJ/mol, 그리고 PP60은 422 kJ/mol이었다.

쌀 전분의 노화 특성에 관한 연구 (Studies on the Retrogradation Properties of Rice Starch)

  • 이찬
    • 한국식품영양학회지
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    • 제16권2호
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    • pp.105-110
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    • 2003
  • 밥의 식미에 영향을 주는 쌀품종별 노화특성에 관한 연구에서 아밀로오스 함량과 gel consistency가 다른 5가지 품종에 대하여 조사하였다. Brabender amylograph에 의한 쌀품종별 호화특성에서는 아밀로오스 함량에 관계없이 hard gel인 품종이 높은 setback 값을 보였다. 저장시의 경도변화에서는 아밀로오스 함량이 높은 품종의 최종경도가 더 높았다. 또한 Avrami equation에 의한 쌀전분겔의 노화특성 연구에서도 아밀로오스 함량이 높은 품종에서 노화속도를 나타내는 지표로서 사용되는 time constant(l/k)값이 더 높은 것으로 나타남에 따라 아밀로오스 함량이 쌀전분의 노화현상에서 매우 중요한 요인라는 것을 알 수 있었다.

용접 열영향부 미세조직 및 재질예측 모델링: II. Fe-C-Mn 강에서 페라이트 결정립크기의 영향을 고려한 Austenitization kinetics 및 오스테나이트 결정립크기 예측모델 (Prediction Model for the Microstructure and Properties in Weld Heat Affected Zone: II. Prediction Model for the Austenitization Kinetics and Austenite Grain Size Considering the Effect of Ferrite Grain Size in Fe-C-Mn Steel)

  • 유종근;문준오;이창희;엄상호;이종봉;장웅성
    • Journal of Welding and Joining
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    • 제24권1호
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    • pp.77-87
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    • 2006
  • Considering ferrite grain size in the base metal, the prediction model for $A_{c3}$ temperature and prior austenite grain size at just above $A_{c3}$ temperature was proposed. In order to predict $A_{c3}$ temperature, the Avrami equation was modified with the variation of ferrite grain size, and its kinetic parameters were measured from non-isothermal data during continuous heating. From calculation using a proposed model, $A_{c3}$ temperatures increased with increasing ferrite grain size and heating rate. Meanwhile, by converting the phase transformation kinetic model that predicts the ferrite grain size from austenite grain size during cooling, a prediction model for prior austenite grain size at just above the $A_{c3}$ temperature during heating was developed.

Synthesis and Crystallization Behaviors of Modified PET Copolymers

  • Hu, Seung-Woo;Myung, Hee-Soo;Bae, Jong-Seok;Yoo, Eui-Sang;Im, Seung-Soon
    • Fibers and Polymers
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    • 제1권2호
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    • pp.76-82
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    • 2000
  • A series of random copolyesters having various compositions were synthesized by bulk copolymerization of bishydroxyethyl terephthalate (BHET) with 1,4-cyclohexane dimethanol (CHDM) or dimethyl isophthalate (DMI). CHDM and DMI content was less than 10 wt%. For the synthesized copolyesters, isothermal crystallization rate, melting behavior, and equilibrium temperature were investigated by calorimetry and by Avrami and Hoffman-Weeks equation. Crystalline lattice and morphology were studied by WAXD and SEM. Regardless of the composition, the value of the Avrami exponent was about 3, which indicates that crystallization mechanism of the copolyester was similar to those of PET homopolymer. Incoporation of CHDM or DMI units in PET backbone decreased the crystallization rate of the copolyesters. Surface free energy of copolyesters was evaluated using the newly proposed equation. The value of surface free energy was about 189$\times$$10^{-6}$/$J^{2}$/$m^{4}$ regardless of comonomer contents. This result is in good agreement with that of PET homopolymer.

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열분석을 이용한 CaO-MgO-Al$_2$O$_3$-SiO$_2$의 결정화 기구의 연구 (The Crystallization Kinetics of CaO-MgO-Al2O3-SiO2 Glass System Using Thermal Analysis)

  • 김형순
    • 한국세라믹학회지
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    • 제29권1호
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    • pp.9-14
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    • 1992
  • Some of non-isothermal analysis methods are applied to CaO-MgO-Al2O3-SiO2 glass system to find the kinetics parameters of crystallisation, activation energy, Avrami component and frequency factor. The results using the non-isothermal analysis were compared to that of microstructure experiment. Analysis of the result has enabled to some methods to be to recommend as being the most appropriate equation to use in a glass system. It was shown that in the thermal analysis using the non-isothermal method of Kissinger, Augis-Bennett, Bansal, and Marotta, the calculation of activation energy is not much different, while Avrami component and frequency factor are different from applied each methods.

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