• Title/Summary/Keyword: Arrhenius 인자

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Effect of Sucrose on the Rheological Properties of Com Starch (Sucrose 첨가가 옥수수전분의 레올로지 특성에 미치는 영향)

  • Chang, Yoon-Hyuk;Lim, Seung-Taik;Yoo, Byoung-Seung
    • Korean Journal of Food Science and Technology
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    • v.33 no.6
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    • pp.700-705
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    • 2001
  • Sucrose첨가가 옥수수 전분호액의 레올로지 특성에 미치는 영향에 대하여 평가하였다. 전분호액은 sucrose 첨가에 관계없이 전단담화 비뉴턴 거동(n=0.37-0.58)을 나타내었으며, 또한 sucrose의 농도가 증가함에 따라 점조도지수$(K,\;K_h)$, 겉보기 점도$({\eta}_{a,100})$값은 크게 감소하였고 항복응력$({\sigma}_{oc},\;{\sigma}_h)$도 감소하는 경향을 나타내었다. 전분호액의 겉보기점도에 대한 온도의존성은 Arrhenius식에 의하여 높은 상관관계를 나타내었으며, 활성화에너지는 각각 10.80-15.59 kJ/mole을 나타내었고 농도가 증가함에 따라 감소하는 경향을 나타내었다. 적용된 주파수$({\omega})$ 범위에서 저장탄성률(G#)의 수치가 손실탄성률(G@)보다 높게 나타났으며 sucrose의 농도가 증가함에 따라 감소하여 탄성 및 점성 성질을 감소시켜 주었다. 이들 동적데이터로부터 전분호액은 sucrose 첨가에 의해 더욱 약한 겔과 같은 구조적 성질을 나타냄을 알 수 있었다. 그러므로 sucrose 첨가는 전분호액 내의 입자들의 재회합을 방해하여 전분호액의 레올로지 특성을 변화시킨다. Sucrose 30%를 첨가한 옥수수 전분호액을 제외한 모든 시료들은 이동인자$(shift\;factor,\;\alpha)$를 사용함으로써 Cox-Merz 중첩 원리에 잘 적용되었다.

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Effect of Polyhedral Oligomeric Silsesquioxane on Cure Characterization of an Epoxy/Amine System (에폭시/아민계의 경화 특성에 미치는 Polyhedral Oligomeric Silsesquioxane의 영향)

  • Gu, Puzhong;Lee, Jong Keun
    • Polymer(Korea)
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    • v.37 no.1
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    • pp.41-46
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    • 2013
  • The glass transition temperature ($T_g$) and conversion (${\alpha}$) were measured for a diglycidyl ether of bisphenol A (DGEBA) epoxy/aromatic amine system incorporated with an organic-inorganic hybrid molecule, polyhedral oligomeric silsesquioxane (POSS). Samples isothermally cured at varying cure temperatures and times were analyzed by differential scanning calorimetry (DSC). $T_g$ vs. ln (time) data at an arbitrary reference were superposed by time-temperature shifts for the kinetically controlled reaction, and the shift factors were used to calculate an Arrhenius activation energy. Influence of POSS was investigated from $T_g$ vs. ${\alpha}$ data, which in turn were fitted with DiBenedetto equation.

Accelerated Life Prediction on Tensile Strength of Oil Resistance HNBR (내유성 HNBR 고무의 인장강도 성능에 대한 가속수명예측)

  • Kim, Kyung Pil;Lee, Yong Seok;Yeo, Yong Heon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.11
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    • pp.233-238
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    • 2020
  • Although the interest in NBR has been increasing due to the recent developments of the aerospace sector, there are few reports on HNBR's aeronautical oil, particularly evaluations of the accelerated life of harsh factors. In this study, the tensile strength was adopted as a performance evaluation factor to evaluate the accelerated life of HNBR used in the aviation field. The accelerated stress factor affecting the performance-aging characteristics was defined as temperature. The acceleration stress factor was determined to be temperature, and the result of measuring the tensile strength change over time. The sample for the acceleration condition was taken out of the oven for a certain period and left at room temperature for 24 hours. The dumbbell type 3 specimens were manufactured according to the standard specified in KS M 6518 and were measured the tensile strength, a factor in accelerated life evaluations. The activation energy was 0.895, and the shape parameter was 1.152 using the Arrhenius model. The characteristic life obtained from the tensile strength of the HNBR specimen immersed in aviation oil at 20℃ was 272,256 hours; the average life was 258,965 hours, and the B10 life was 38,624 hours.

Investigation of the processing characteristics of soybean sprouts after germination of HaePum during a long storage period with different temperature and humidity (장기 저장 중 저장 온도와 습도에 따른 해품 콩의 콩나물 가공적성 연구)

  • Lee, Yun Ju;Yoon, Won Byong
    • Journal of Applied Biological Chemistry
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    • v.63 no.1
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    • pp.1-8
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    • 2020
  • This study investigated the processing characteristics of soybean (HaePum) sprouts based on temperature (5, 15 and room temperature), period (0, 6 and 12 mon) and relative humidity (20, 40, 60, and 80%) during storage. The initial germination rate of soybean sprouts was 76.02±6.32%, which significantly reduced to 57.18±8.51%, and 0% as the storage temperature of soybean increased for a period of 12 mon. The germination rate of soybean sprouts with 30 ℃ and 80% RH decreased after 4 mon of storage to 4.94%. The yellowness of cotyledon of soybean sprouts was not significantly changed during the 12 mon period of storage at 5 ℃, whereas, soybean sprouts stored at 15 ℃ and room temperature demonstrated decreased yellowness. However, the stress of cotyledon decreased with an increase in both storage temperature and time, and the hardness of hypocotyl decreased with an increase of storage time. The stress of cotyledon affected by high temperature (30 ℃) and humidity (80%) during 4 mon was reduced to 44.39±9.38 g/㎟. The asparagine content of soybean sprouts showed a similar result with the germination rate due to the amount of hypocotyl. Therefore, lower temperatures and shorter storage times are suitable for soybean sprout processing. The first order kinetic model and Arrhenius equation (activation energy =29.56 kJ/mol) were able to predict the yield of sprout at various storage temperatures and periods.

The Acclerated Life Test of Hard Disk In The Environment of PACS (PACS 환경에서 하드디스크의 가속 수명시험)

  • Cho, Euy-Hyun;Park, Jeong-Kyu;Chae, Jong-Gyu
    • Journal of Digital Contents Society
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    • v.16 no.1
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    • pp.63-70
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    • 2015
  • In this paper, we estimate the life cycle from acceleration life test about the hard disk of disk array of image storage of PACS. Webuil distribution was selected by the Anderson-Darling goodness-of-fit test with data of down time at $50^{\circ}C$ and $60^{\circ}C$. The equality test of shape parameter and scale parameter was conducted, so that the probability distribution estimated from data of down time at $50^{\circ}C$ and $60^{\circ}C$ was not statistically significant. The shape parameter was 1.0409, The characteristic life was 24603.5 hours at normal user condition($30^{\circ}C$) by the analysis of weibull-arrhenius modeling which included the acceleration factor of temperature, and The activation energy was 0.5011 eV through arrhenius modeling. The failure analysis of the failure samples of acceleration test and the samples of market return was conducted, so that the share percentage of failure mode was detail difference but the rank of share percentage was almost same. This study suggest the test procedure of acceleration test of hard disk drive in PACS using environment, and help the life estimation at manufacture and use.

The Study on Thermal Analysis and Thermodynamic Characteristics of Spinel Compounds(ZnCo2O4, NiCo2O4) (스피넬 구조를 가지는 전이금속화합물(ZnCo2O4, NiCo2O4)의 열적 분석 및 열역학적 특성 연구)

  • Kim, Jae-Uk;Ji, Myoung-Jin;Cha, Byung-Kwan;Kim, Chul-Hyun;Jang, Won-Cheoul;Kim, Jong-Gyu
    • Journal of the Korean Chemical Society
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    • v.54 no.2
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    • pp.192-197
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    • 2010
  • The spinel compound was obtained by the thermal decomposition of Zn-Co and Zn-Ni gel prepared by sol-gel method using oxalic acid as a chelating agent. The formation of spinel compound has been comfirmed by thermogravimetric analysis (TGA), x-ray powder diffraction (XRD) and infrared spectroscopy (IR). The particle size of 13 nm~16 nm was calculated by Scherrer's equation. The sol-gel method provides a practicable and effective route for the synthesis of the spinel compound at low temperature ($350^{\circ}C$). The kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) for each compound were found by means of the Kissinger method and Arrhenius equation. The decomposition of spinel compound has an activation energy about 155 kJ/mol. Finally, the thermodynamic parameters (${\Delta}G^{\varphi}$, ${\Delta}H^{\varphi}$, ${\Delta}S^{\varphi}$) for decomposition of spinel compound was determined.

A Study on Reaction Rate of Solid SCR for NOx Reduction of Exhaust Emissions in Diesel Engine (디젤엔진 배출가스 질소산화물 저감을 위한 Solid SCR의 반응률에 관한 연구)

  • Lee, Hoyeol;Yoon, Cheon Seog;Kim, Hongsuk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.6
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    • pp.183-194
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    • 2013
  • Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.

An Extraction of Detailed Isoconversional Kinetic Scheme of Energetic Materials using Isothermal DSC (등전환법과 등온 DSC를 이용한 고에너지 물질의 정밀 반응모델 개발)

  • Kim, Yoocheon;Park, Jungsu;Kwon, Kuktae;Yoh, Jai-ick
    • Journal of the Korean Society of Propulsion Engineers
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    • v.20 no.2
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    • pp.46-55
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    • 2016
  • The kinetic analysis of a heavily aluminized cyclotrimethylene-trinitramine(RDX) is conducted using differential scanning calorimetry(DSC), and the Friedman isoconversional method is applied to the DSC experimental data. The pre-exponential factor and activation energy are extracted as a function of the product mass fraction. The extracted kinetic scheme does not assume multiple chemical steps to describe the complex response of energetic materials; instead, a set of multiple Arrhenius factors is constructed based on the local progress of the exothermic reaction. The resulting reaction kinetic scheme is applied to two thermal decomposition tests for validating the reactive flow response of a heavily aluminized RDX. The results support applicability of the present model to practical thermal explosion systems.

Storage Reliability Assessment of Springs for Turbo Engine Components (터보엔진 구성품용 스프링의 저장 신뢰성 평가)

  • Chang, Mu-Seong;Lee, Choong-Sung;Park, Jong-Won;Kim, You-Il;Kim, Sun Je
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.4
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    • pp.42-49
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    • 2019
  • This paper presents a method to predict the storage reliability of springs for turbo engine components based on an accelerated degradation test. The reliability assessment procedure for springs is established to proceed with the accelerated degradation test. The spring constant is selected as the performance degradation characteristic, the temperature is determined to be the stress factor that deteriorates the spring constant. The storage tests are performed at three temperature test conditions. The spring constant is measured periodically to check the degradation status of the springs. Failure times of the springs are predicted by using the degradation model. Finally, the storage lifetime of the springs at normal use conditions is predicted using an accelerated model and failure times of all test conditions.

Quality Factor Determination and Shelf-Life Prediction of Emulsified Ginseng Drink (인삼 유화 음료의 품질 인자 규명 및 저장 수명 예측)

  • Baik, Eun-Kyung;Seo, Yong-Ki;Lee, Geun;Lee, Dong-Un;Park, Seok-Jun;Lee, Jin-Hee;Lee, Kang-Pyo;Kim, Dong-Seob;Hur, Nam-Yun;Baik, Moo-Yeol
    • Korean Journal of Food Science and Technology
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    • v.37 no.4
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    • pp.597-602
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    • 2005
  • Quality factors of emulsified ginseng drink were determined during storage at various temperatures, and its shelf-life was predicted based on changes in emulsion stability, acidify, viscosity, and yellowness. Viscosity was highly dependent on storage temperature. Emulsion stability changed rapidly during early storage period (1st step), then slowly thereafter (2nd step). $Q_{10}$ values of emulsion stability were 2.50 and 1.38 for 1st and 2nd steps, respectively. Viscosity, acidity, and yellowness showed $Q_{10}$ values of 3.45, 1.77, and 1.99, respectively. Although $Q_{10}$ value of 2 has been generally used to predict shelf stability of food materials, our results suggest adopting same $Q_{10}$ value to predict shelf stability of emulsified ginseng drink is not appropriate.