• 한국신뢰성학회지:신뢰성응용연구
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• 제11권2호
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• pp.127-140
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• 2011

This paper presents an accelerated life test of aviation taxiway lights installed in the airport to help safe navigation of airplanes at night or in bad weather. Recently halogen lamps of taxiway lights are replaced by LED ones and their reliability needs yet to be verified. Thus, effective test conditions are designed reflecting the failure modes and mechanisms from the previous studies on LED, which include the accelerated degradation process. The test is performed under the temperature $70^{\circ}C$ and $90^{\circ}C$ for two types of LED lights, taxiway center line lights(TCLL) and taxiway edge lights (TEDL). The failure time data were analyzed using lognormal distribution and Arrhenius model to find the life-stress relationship, acceleration factor and life characteristics under the normal condition temperature $30^{\circ}C$.

• 한국세라믹학회지
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• 제40권7호
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• pp.615-619
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• 2003

Temperature and frequency dependence of dielectric and electrical properties was investigated in cerium and manganese doped Sr$\_$0.6/Ba$\_$0.4/Nb$_2$O$\_$6/(60SBN) ceramic system. Structural deformation of 60SBN by dopants did not appeared. 1350$^{\circ}C$-10 h sintered specimen had higher densification than 1250$^{\circ}C$-10 h sintered one, to which dielectric properties are related. That the feature of dielectric maxima peaks was typical Diffusive Phase Transition (DPT), it was explained by "random-field Ising model". Even though 60SBN has large dielectric loss at high frequency above 100 ㎑, it is desirable for optical applications because of low dielectric loss at low frequency. From Arrhenius plot of temperature, the activation energy was calculated to 0.45-0.49 eV.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.222-232
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• 2009

In this study, the real site test conditions were considered and applied to suggest the improved test method for geosynthetics chemical resistance. For this, index and performance tests were done to specify and regulate the more approached test method. Accelerated model by Arrhenius equation was applied to interpretate the experimental data. Through analysis and comparison the overall experimental results, we could suggest the possibility and setup the advanced chemical resistance test method for geosynthetics.

• Advances in nano research
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• 제10권5호
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• pp.437-448
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• 2021

In this article, an analytically and numerically 3D nanoliquid flow by a porous rotatable disk is presented in the presence of gyrotactic microorganisms. The mathematical model in the form of partial differential system is transmuted into dimensionless form by utilizing the appropriate transformation. The homotopy analysis approach is applied to attain the analytic solution of the problem. The effect of promising parameters on velocity distribution, temperature profile, nanoparticles volume fraction and motile microorganism distribution field are evaluated through graphs and in tabular form. The existence of Brownian motion and thermophoresis impacts are more proficient for heat transfer enhancement. Further the unique features like heat absorption/generation and energy activation are also examined for the present flow problem. The obtained results are compared with the earliear investigation to check the accuracy of present model.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.595-601
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• 2020

10년 이상 보관된 니트로셀룰로오스 (Nitrocellulose, 니트로셀룰로오스) 재질의 화약용기 안전 검사를 진행하는 과정 중 화약이 보관되어진 용기에 균열이 발생한 것을 확인하여 고장 원인 분석 시험을 실시하였다. 고장이 발생한 데에 영향을 준 요인을 선별하기 위해 먼저 고장수목분석(Fault Tree Analysis, FTA)을 통해 고장 요인 및 원인에 대해 탐구하였으며, 보관 시 발생할 수 있는 내·외부적인 요인 및 환경에 대한 영향성을 확인한 결과 열에 의해 화학 반응이 가속화되어 발생한 화약용기의 물성 변화가 고장의 원인인 것으로 추정하였다. 이를 확인하기 위해 자연 노화된 화약용기를 이용하여 열충격시험, 양립성 시험 등의 환경시험을 수행하여 고장의 원인 분석을 수행하였으며, 가속노화시험을 통해 고장 재현 시험을 실시하였다. 이를 통해 앞선 고장수목분석 결과와 같이 열과 화약에 의해 화학 반응이 가속화되는 것을 확인할 수 있었으며, 화약용기의 물성이 변화하는 것을 확인하였다. 또한, 열 노화에 의한 수명 추정을 위해 아레니우스 모델(Arrhenius Model)을 이용하여 화약용기의 사용 수명을 추정하였다.

• Elastomers and Composites
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• 제42권4호
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• pp.232-237
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• 2007

가스켓 재료로서 널리 사용되고 있는 FKM, VMQ, EPDM, NBR을 연료전지 스택용 가스켓으로써의 적합성을 평가하기 위하여, 각각의 재료특성을 이용하여 최적상태의 배합물을 제작하고, 배합물의 특성을 살펴보았다. 최적의 상태를 만족하도록 만든 배합물에서 NBR 재료는 장기 화학적 물성에서, VMQ는 금속이온 용출성에서, EPDM은 가스투과성이 FKM에 비하여 열세로 나타났다. 배합물 물성에서 우수하다고 판단된 FKM으로 연료전지 스택용 가스켓을 제작하여 leak 평가를 실시한 결과, 체결압이 낮을수록, sealing pressure가 높을수록 짧은 시간에서 leak가 발생하였다. 또 Arrhenius Model을 이용하여 수명예측을 실시한 결과, $80^{\circ}C$에서 연속운전 시 가스켓의 수명은 60,000시간 이상 가능한 것으로 예측되었다.

• 디지털융복합연구
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• 제19권6호
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• pp.113-132
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• 2021

특허수명은 특허가치를 평가하는 척도로 사용되어 왔다. 본 연구에서는 특허수명을 예측하여 개별특허의 가치를 평가함에 있어, 특허의 내적가치요소와 외적가치요소를 하나의 모델로 평가하기 위하여 화학반응속도 추정식으로 널리 알려진 아레니우스식을 사용한 새로운 평가모델을 제시하였다. 한국의 소멸된 특허데이터를 활용하여 평가모델의 성능을 검증하였으며, 선행연구에서 특허평가모델로 사용되었던 SVM, Logistic reg., ANN 모델과 성능을 비교하였다. 결과적으로, 제안한 평가모델이 다른 모델 보다 정확도가 높았으며, 특허권자의 특성을 고려한 상대체감비용지수 반영 시 여러 평가모델에서 정확도가 상승하는 경향을 보였다. 또한, 특허의 예측수명등급과 특허의 실제수명과는 강한 상관관계가 있었다. 이러한 평가모델은 대량의 특허를 객관적으로 신속하게 평가할 수 있으며 특허의 유지여부에 대한 의사결정 혹은 기술거래나 평가에 활용할 수 있다. 특히, 평가목적에 따라 특허만을 평가하거나 사업화주체나 기술적 특성을 고려한 평가가 필요한 경우에 각각 사용될 수 있다.

• 한국식품저장유통학회지
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• 제30권4호
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• pp.573-588
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• 2023

The purpose of this study was to monitor changes in the quality of ginseng and predict its shelf-life. As the storage period of ginseng increased, some quality indicators, such as water-soluble pectin (WSP), CDTA-soluble pectin (CSP), cellulose, weight loss, and microbial growth increased, while others (Na₂CO₃-soluble pectin/NSP, hemicellulose, starch, and firmness) decreased. Principal component analysis (PCA) was performed using the quality attribute data and the principal component 1 (PC1) scores extracted from the PCA results were applied to the multivariate analysis. The reaction rate at different temperatures and the temperature dependence of the reaction rate were determined using kinetic and Arrhenius models, respectively. Among the kinetic models, zeroth-order models with cellulose and a PC1 score provided an adequate fit for reaction rate estimation. Hence, the prediction model was constructed by applying the cellulose and PC1 scores to the zeroth-order kinetic and Arrhenius models. The prediction model with PC1 score showed higher R² values (0.877-0.919) than those of cellulose (0.797-0.863), indicating that multivariate analysis using PC1 score is more accurate for the shelf-life prediction of ginseng. The predicted shelf-life using the multivariate accelerated shelf-life test at 5, 20, and 35℃ was 40, 16, and 7 days, respectively.

• Computers and Concrete
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• 제19권6호
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• pp.659-666
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• 2017

Based on the Arrhenius equations, several hydration exothermic models that precisely calculate the influence of concrete's self-temperature duration on its hydration exothermic rate have been presented. However, the models' convergence is difficult to achieve when applied to engineering projects, especially when the activation energy of the Arrhenius equation is precisely considered. Thus, the models' convergence performance should be improved. To solve this problem and apply the model to engineering projects, the relationship between fast iteration and proper expression forms of the adiabatic temperature rise, the coupling relationship between the pipe-cooling and hydration exothermic models, and the influence of concrete's self-temperature duration on its mechanical properties were studied. Based on these results, the rapid convergence of the hydration exothermic model and its coupling with pipe-cooling models were achieved. The calculation results for a particular engineering project show that the improved concrete hydration exothermic model and the corresponding mechanical model can be suitably applied to engineering projects.

• 한국세라믹학회지
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• 제33권6호
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• pp.645-652
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• 1996

The ionic conductivity of NASICON (Na Super Ionic Conductor) solid electrolyte was simulated by using Monte Carlo Method (MCM)based on a hopping model. We assumed that the conduction path of Na ions is Na1→mid-Na→Na2 where the mid-Na sites are shallow potential sites to induce 'a breathing-like movement' of Na ions in the NASICON framework. The minimum of charge correlation factor Fc and the maximum of appeared at nearby x=2.0 The occupancy of mid-Na site affected the depth of potential barrier and the conduc-tivity of the NASICON. At above x=0.3 ln σT vs. 1/T* plots have been shown Arrhenius behavior but in (VWfc)vs. 1/T* have been shown the Arrhenius type tendency at x=1 MCM results accorded with the experi-mental procedure. The role of mid-Na on Na+ ion conduction could be explained by an additional driving force and a breating-like movement model for motions of Na+ ions in the NASICON framework. As we couldn't clearly remarked the model which is the better it seems reasonable to conclude that these hypothesies are suitable to explain the FIC behavior at NASICON.