• Title, Summary, Keyword: Activation Energy

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A Model for Activation Energy of Moisture Diffusion in Wood (수분확산(水分擴散)의 활성화(活性化)에너지 모델)

  • Kang, Ho-Yang
    • Journal of the Korean Wood Science and Technology
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    • v.20 no.4
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    • pp.21-30
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    • 1992
  • An activation energy equation for moisture diffusion in wood was developed with an assumption that activation energy is directly proportional to wood specific gravity. Theoretical activation energies obtained from the activation energy equation were revealed to be always lower than actual activation energies, which implies that activation energy isn't affected only by wood specific gravity. The other affecting factors are possibly anatomical structures of wood which determine a ratio of vapor diffusion to bound water diffusion in wood. For the convenience of estimating actual activation energy by using the activation energy equation, thirteen kinds of species were categorized into three groups according to their anatomical structures.

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A Study on the Activation Energy of Maturity Function for Prediction of Concrete Strength (콘크리트 강도예측을 위한 적산온도 함수의 활성화에너지에 관한 연구)

  • 장종호;강용식;김용로;길배수;남재현;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.81-84
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    • 2002
  • Activation energy value is different according to cement, admixture and water-cement ratio also the relation of age-temperature is as non-linear as activation energy value is large. So to make accurate explanation for the effect of temperature on concrete strength development property, it is necessary to investigation for activation energy value. This study compares activation energy value recommended by Freiesleben and ASTM with activation energy value obtained by consequence of mortar examination according to ASTM C 1074-93. As the result of this study, activation energy value obtained by the study is 37.19KJ/mol, and in case of activation energy value obtained by the study explain temperature's influence about concrete strength development more accurate than activation energy value recommend by Freiesleben and ASTM.

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Activation energy standardization of White LED Phosphor (White LED 형광체의 활성화 에너지 정형화)

  • Jang, In-Hyeok;Kim, Su-Kyoung;Han, Ji-Hoon;Lee, Chang-Hoon;Lim, Houng-Woo
    • Journal of Applied Reliability
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    • v.13 no.2
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    • pp.117-127
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    • 2013
  • In this paper, we studied the correlation between the activation energy($E_a$) of the raw materials and the structural characteristics of the White LED PKGs. The samples used in the study were composed of low power LED 3type and high power LED 5type. To calculate the activation energy($E_a$) of the White LED PKGs conducted three conditions of high temperature operation test based on the Arrhenius model. The number of samples used in the experiment is 10, respectively. The $T_j$ of Conditions and target specifics expressed $T_{j1}$, $T_{j2}$, $T_{j3}$. The activation energy ($E_a$) of the samples was calculated based on the value of the actually measured lifetime. We investigated the correlation between the activation energy ($E_a$) of the raw materials and the structural characteristics of the White LED PKGs. As a result, White LED PKGs activation energy($E_a$) value was confirmed that the material properties affected more than the structural characteristics of the LED PKGs and we found that activation energy of each LED Model has difference. Normally, The activation energy of phosphor of YAG type was indicated from 0.21 to 0.25[eV] and Silicate type was indicated from 0.12 to 0.16[eV]. According to the results, we confirmed that the activation energy of phosphor of YAG type is higher more than The activation energy of phosphor of Silicate type.

An Experimental Study on the Relation of Compressive Strength and the Equivalent Age according to the Kind of Cement (시멘트종류에 따른 압축강도와 등가재령 관계에 관한 실험적 연구)

  • 나철성;장종호;길배수;김정일;남재현;김무한
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.13.1-16
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    • 2003
  • There is no study that application of the maturity using H.S.C and H.S.C. Also activation energy has different values according to the cement, admixture and water-cement ratio. Therefore to make accurate explanation for the effect of temperature on concrete strength development properties, it is necessary that activation energy value according to the kind of cement is reviewed. This study compares and estimates equivalent age using activation energy value obtained by this experiment and Freiesleben activation energy value with compressive strength of concrete. As the result of this study, activation energy value obtained by this study has more accurate explanation of temperature's influence on concrete strength development than Freiesleben activation energy value.

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An Experimental Study on the Relation of Compressive Strength and the Equivalent Age according to the Kind of Cement (시멘트종류에 따른 압축강도와 등가재령 관계에 관한 실험적 연구)

  • Na, Chul-Sung;Jang, Jong-Ho;Khil, Bae-Su;Kim, Jung-II;Nam, Jae-Hyun;Kim, Moo-Han
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.13-16
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    • 2003
  • There is no study that application of the maturity using H.B.C and H.S.C. Also activation energy has different values according to the cement, admixture and water-cement ratio. Therefore to make accurate explanation for the effect of temperature on concrete strength development properties, it is necessary that activation energy value according to the kind of cement is reviewed. This study compares and estimates equivalent age using activation energy value obtained by this experiment and Freiesleben activation energy value with compressive strength of concrete. As the result of this study, activation energy value obtained by this study has more accurate explanation of temperature's influence on concrete strength development than Freiesleben activation energy value.

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Thickness Dependent Temperature Accelerated Dielectric Break-down Strength of On-wafer Low Dielectric Constant Polymer Films

  • Kim, H. K.;Lee, S. W.;F. G. Shi;B. Zhao
    • KIEE International Transactions on Electrophysics and Applications
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    • v.2C no.6
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    • pp.281-286
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    • 2002
  • The temperature accelerated dielectric breakdown strength of on-wafer low-k dielectric polymer films with thicknesses ranging from 94 nm to 1141 nm is investigated by using the current-voltage characteristic measurements with MIS structures. The temperature dependence of dielectric strength is demonstrated to be Arrhenious for all thicknesses. However, the activation energy is found to be strongly thickness dependent. It follows an exponential relationship rather than being a single value, i.e., the activation energy increase significantly as film thickness increases for the thickness below 500 nm, but it is almost constant for the thickness above 500 nm. This relationship suggests that the change of the activation energy corresponding to different film thickness is closely related to the temperature dependence of the electron trapping/detrapping process in polymer thin films, and is determined by both the trapping rate and the detrapping rate. Thinner films need less energy to form a conduction path compared to thicker films. Hence, it leads to smaller activation energy in thinner films, and the activation energy increases with the increase in film thickness. However, a nearly constant value of the activation energy is achieved above a certain range of film thickness, indicating that the trapping rate and detrapping rate is almost equal and eventually the activation energy approaches the value of bulk material.

Study on the Activation Energy of Charge Migration for 3D NAND Flash Memory Application (3차원 플래시 메모리의 전하 손실 원인 규명을 위한 Activation Energy 분석)

  • Yang, Hee Hun;Sung, Jae Young;Lee, Hwee Yeon;Jeong, Jun Kyo;Lee, Ga won
    • Journal of the Semiconductor & Display Technology
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    • v.18 no.2
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    • pp.82-86
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    • 2019
  • The reliability of 3D NAND flash memory cell is affected by the charge migration which can be divided into the vertical migration and the lateral migration. To clarify the difference of two migrations, the activation energy of the charge loss is extracted and compared in a conventional square device pattern and a new test pattern where the perimeter of the gate is exaggerated but the area is same. The charge loss is larger in the suggested test pattern and the activation energy is extracted to be 0.058 eV while the activation energy is 0.28 eV in the square pattern.

Optimization of microcrystaliline silicon thin film solar cells using simulation (i-layer 두께와 back reflect layer 유무가 미세결정 실리콘 박막태양전지에 미치는 영향)

  • Park, Seung-Man;Lee, Young-Suk;Jung, Sung-Wook;Yi, Jun-Sin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.437-437
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    • 2009
  • 현재 상용화되어 있는 결정질 태양전지의 경우 높은 실리콘 가격으로 인해 저가화에 어려움을 격고 있다. 따라서 태양전지 저가화의 한 방법으로 박막태양전지가 주목을 받고 있다. P-I-N 구조의 박막태양전지에서 I-layer 각 층의 thickness, activation energy, energy bandgap은 고효율 달성을 위한 중요한 요소이다. 본 논문에서는 박막태양전지 P-I-N layer의 가변을 통하여 고효율을 달성하기 위한 simulation을 수행하였다. 가변 조건으로는 p-layer의 thickness, activation energy 그리고 energy bandgap을 단계별로 변화시켰고 i-layer는 thickness를 n-layer는 thickness와 activation energy를 가변하여 최적의 조건을 찾아 분석하였다. 최종 simulation 결과 p-layer의 thickness 5nm, activation energy 0.3eV 그리고 energy bandgap 1.8eV에서, i-layer thickness 400nm, n-layer thickness 30nm, activation energy 0.2eV에서 최고 효율 11.08%를 달성하였다.

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Optimization of p-i-n amorphous silicon thin film solar cells using simulation (시뮬레이션을 통한 p-i-n 비정질 실리콘 박막 태양전지의 최적화)

  • Park, Seung-Man;Lee, Young-Suk;Jung, Sung-Wook;Yi, Jun-Sin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.436-436
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    • 2009
  • 현재 상용화되어 있는 결정질 태양전지의 경우 높은 실리콘 가격으로 인해 저가화에 어려움을 격고 있다. 따라서 태양전지 저가화의 한 방법으로 박막태양전지가 주목을 받고 있다. P-I-N 구조의 박막태양전지에서 각 층의 thickness, activation energy, energy bandgap은 고효율 달성을 위한 중요한 요소이다. 본 논문에서는 박막태양전지 P-I-N layer의 가변을 통하여 고효율을 달성하기 위한 simulation을 수행하였다. 가변 조건으로는 p-layer의 thickness, activation energy 그리고 energy bandgap을 단계별로 변화시켰고 i-layer는 thickness를 n-layer는 thickness와 activation energy를 가변하여 최적의 조건을 찾아 분석하였다. 최종 simulation 결과 p-layer의 thickness 5nm, activation energy 0.3eV 그리고 energy bandgap 1.8eV에서, i-layer thickness 400nm, n-layer thickness 30nm, activation energy 0.2eV에서 최고 효율 11.08%를 달성하였다.

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The Analysis on the Activation Procedure of Polymer Electrolyte Fuel Cells

  • Jang, Jong-Mun;Park, Gu-Gon;Sohn, Young-Jun;Yim, Sung-Dae;Kim, Chang-Soo;Yang, Tae-Hyun
    • Journal of Electrochemical Science and Technology
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    • v.2 no.3
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    • pp.131-135
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    • 2011
  • It is, in general, believed that during the activation process, the proton conductivity increases due to wetting effect and the electrochemical resistance reduction, resulting in an increase in the fuel cell performance with time. However, until now, very scant information is available on the understanding of activation processes. In this study, dominant variables that effect on the performance increase of membrane electrode assemblies (MEAs) during the activation process were investigated. Wetting, pore restructuring and active metal utilization were analyzed systematically. Unexpectedly, the changes for both ohmic and reaction resistance characterized by the electrochemical impedance spectroscopy (EIS) after initial wetting process were much smaller when considering the degree of cell performance increases. However, the EIS spectra represents that the pore opening of electrode turns into gas transportable structure more easily. The increase in the performance with activation cycles was also investigated in a view of active metals. Though the particle size was grown, the number of effective active sites might be exposed more. The impurity removal and catalytic activity enhancement measured by cyclic voltammetry (CV) could be a strong evident. The results and analysis revealed that, not merely wetting of membrane but also restructuring of electrodeand catalytic activity increase are important factors for the fast and efficient activation of the polymer electrolyte fuel cells.