2009·2015 개정 교육과정 화학 I 및 화학 II 교과서 및 교사용 지도서에 제시된 산·염기 모델 내용에 대한 ‘이그노런스’ 분석

류은주,백성혜 대한화학회 2020 대한화학회지 Vol.64 No.3

The purpose of this study was to analyze chemistry textbooks and teachers’ guidebooks from the perspective of ‘Ignorance’, one of the important features of model. This is because the emphasis is on developing modeling capabilities for students in the 2015 Revised Curriculum. For this, Arrhenius model and Brønsted–Lowry model were selected as acid and base models in neutralization reaction which are important contents in chemistry curriculum. The analysis criteria of this study were extracted by analyzing previous studies and four general chemistry textbooks dealing with ‘Ignorance’ related to acid and base neutralization reaction. Based on the analysis criteria, we analyzed nine chemistry I textbooks and teacher’s guides and six chemistry II textbooks and teacher’s guides of the 2015 revised curriculum. In addition, we analyzed contents of four chemistry I textbooks and teacher’s guides and three chemistry II textbooks and teacher‘s guides in the 2009 revised curriculum for comparison according to revised curriculums. We analyzed the contents related to the concept of ‘neutralization reaction’, ‘neutrality’, ‘quantitative relation of neutralization reaction’, ‘degree of ionization’, and ‘ionization constant’. Based on the results of this study, we proposed a way to present ‘Ignorance’ of the models in teachers’ guidebooks that chemistry teachers can understand ‘Ignorance’ of model and teach modeling capabilities for students. 이 연구에서는 모델의 중요한 특징 중 하나인 ‘이그노런스’의 관점으로 화학 교과서 및 교사용 지도서의 내용을 분석하 였다. 이는 2015 개정 교육과정에서 학생들의 모델링 역량을 기르는 것을 강조하고 있기 때문이다. 화학 교육과정에서 중요하게 다루는 내용인 산과 염기의 중화반응에 관련된 모델로 Arrhenius 모델과 Brønsted–Lowry 모델을 선정하고, 이에 관련된 ‘이그노 런스’를 다룬 선행 연구와 대학 일반화학 교재 4종을 분석하여 연구의 분석 기준을 추출하였다. 추출한 분석 기준으로 2015 개 정 교육과정의 화학 I 교과서 및 교사용 지도서 9종과 화학 II 교과서 및 교사용 지도서 6종을 분석하였다. 또한 개정 교육과정에 따른 내용의 차이를 비교하기 위해 2009 개정 교육과정의 화학 I 교과서 및 교사용 지도서 4종 그리고 화학 II 교과서 및 교사용 지도서 3종도 분석하였다. ‘중화 반응’ 개념, ‘중성’ 개념, ‘중화 반응의 양적 관계’, ‘이온화도’, ‘이온화 상수’에 관련된 내용을 중 심으로 분석하였다. 연구 결과를 토대로, 모델의 ‘이그노런스’를 화학 교사들이 이해하고 학생들의 모델링 역량을 길러줄 수 있 도록 교사용 지도서에 이와 관련된 내용을 제시하는 방안을 제안하였다.

Research on constitutive model of aluminum alloy 7075 thermal deformation based on deep neural network

Guan Wang,Pei Zhang,Linyuan Kou,Yan Wu,Tianxiang Wen,Xin Shang,Zhiwen Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2

The hot deformation behavior of the Al-Zn-Mg-Cu alloy was studied by isothermal tensile tests in the temperature range of 200-350 °C and the strain rate range of 0.001-0.1 s -1 . A data-driven deep neural network (DNN) constitutive model and a phenomenological Arrhenius constitutive model were developed for the studied alloy model. The parameters of the DNN model were optimized to improve the prediction accuracy of flow stress. The results show that the accuracy of predictions of the DNN model is better than the Arrhenius model for the hot deformation behavior of 7075 aluminum alloy. The average absolute relative error and correlation coefficient of the DNN model is 1.70 % and 0.9996, respectively. The accuracy of the constitutive model of Arrhenius is relatively low for 7075 aluminum alloy in the range 200-350 °C, 0.001-0.1 s -1 . The optimal network depth and the number of neurons per layer for the analytically optimized DNN constitutive model are 6 and 28, respectively. In addition, the developed DNN model can be effectively applied in intelligent manufacturing, such as short-process highefficiency hot stamping and other plastic-forming technologies.

Acoustic study on the thermal aging of sound-absorbing polyurethane foam

양성수,허준,Jung Wook Lee,Sung Hwan Park,강연준 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

This research aims to explore the degradation process of sound-absorbing polyurethane foam (PUF) and create a dependable aging model. To accomplish this, accelerated testing was carried out in a heat chamber under various conditions, measuring transport parameters and sound absorption coefficients. The Layton model and Arrhenius equations were used to construct the aging model, which demonstrated a strong agreement with the collected data. With the aging model presented in this study, it is possible to predict the acoustic behavior of PUF at any temperature and aging duration. The effectiveness of the developed aging model was subsequently confirmed through test samples. These findings can serve as a fundamental reference for devising a predictive model for the acoustic behavior of PUFs experiencing thermal aging, as well as offer valuable insights for designing an accelerated testing approach.

온도상태에 따른 신축관 이음의 수명예측에 관한 연구

오정수(Jung-Soo Oh),이봉수(Bong-Soo Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.10

본 연구에서는 플랜트 설비 부품류 중 충격에 취약한 신축관 이음을 대상으로 수충격 발생 시 신축관 이음의 신축량을 유압식 액추에이터의 작동데이터로 적용하여 진동내구 시험을 수행하였다. 진동내구 시험 시 내구수명의 가속 요소로 신축관 내부의 온도상태를 가정하고 온도상태를 30℃부터 50℃ 및 65℃로 가속화한 진동내구 시험을 진행하였다. 각 조건별 온도상태별 수명데이터들은 아레니우스 모델식을 따른다고 가정하고 각 수명데이터를 선형화하여 선형식의 상수값과 활성화 에너지 계수를 유도하였다. 또한 유도된 모델식으로부터 85℃ 경우의 예측 수명과 85℃ 온도상태에서의 시험 수명결과와 비교를 통해 작은 편차 범위내에서 유도된 모델식의 유효성을 검증하였다. 한편, 시험 중과 시험 후 발견된 신축관의 고장모드에서는 누수 및 벨로우즈 부 내부 슬리부의 이탈과 내부변형 등을 확인할 수 있었다. 향후 본 연구는 진동내구 수명의 가속요인인 온도상태 외 압력상태 등 다양한 수명변수를 적용한 복합수명예측 모델식을 개발하고 검증할 예정이다. In this study, an expansion joint that is susceptible to waterhammer was tested for its vibration durability. The operation data for the hydraulic actuator was the expansion length of the expansion joint when the waterhammer occurred. In the case of the vibration durability test, the internal temperature status of the expansion joint was assumed to be a stress factor and a lifespan prediction model was assumed to follow the Arrhenius model. A test was carried out by increasing the internal temperature status at 30 ℃, 50 ℃, and 65 ℃. By a linear transformation of the lifespan data for each temperature, a constant value and activation energy coefficient was induced for the Arrhenius equation and verified by comparing the value of a lifetime prediction model with the experimental value at 85℃. The failure modes of the ongoing or finished test were leakage, bellows separation, and internal deformation. In the future, a composite lifespan prediction model, including two more stress factors, will be developed.

A Comparative Study on Arrhenius-Type Constitutive Models with Regression Methods

Lee, Kyunghoon,Murugesan, Mohanraj,Lee, Seung-Min,Kang, Beom-Soo The Korean Society for Technology of Plasticity 2017 소성가공 : 한국소성가공학회지 Vol.26 No.1

A comparative study was performed on strain-compensated Arrhenius-type constitutive models established with two regression methods: polynomial regression and regression Kriging. For measurements at high temperatures, experimental data of 70Cr3Mo steel were adopted from previous research. An Arrhenius-type constitutive model necessitates strain compensation for material constants to account for strain effect. To associate the material constants with strain, we first evaluated them at a set of discrete strains, then capitalized on surrogate modeling to represent the material constants as a function of strain. As a result, disparate flow stress models were formed via the two different regression methods. The constructed constitutive models were examined systematically against measured flow stresses by validation methods. The predicted material constants were found to be quite accurate compared to the actual material constants. However, notable mismatches between measured and predicted flow stresses were revealed by the proposed validation techniques, which carry out validation with not the entire, but a single tensile test case.

표백후-형광회복의 개선된 분석법과 그 적용

박상권 동국대학교 산업기술연구원 1998 산업기술논문집 Vol.11 No.-

표백후-형광회복의 전통적인 모델과 그 분석방법은 몇 가지 한계가 있으며, 이로 인하여 적지않은 오차가 발생된다. 본 연구의 목적은 이러한 단점이 개선된 분석방법을 발전시키는 것이다. 전통적인 세가지 FRAP 모델을 비교하여 개선된 모델을 결정하였는데, 표백후 시간 t가 0.18τ_d보다 작을 때는 Lardner의 모델을, 그 보다 클 때는 Soumpasis의 모델을 사용하는 것이다. 또한, 오차최소화 알고리즘을 바탕으로 짜여진 컴퓨터 프로그램을 이용하는 개선된 분석방법이 제안되었고, 이에 의해 2차원 분자확산계수 (D_s) 와 고정분자의 분율을 동시에 구할 수 있었다. 이 분석방법이 silica 표면 사이에 제한된 Langmuir-Blodgett 필름에 대해 얻어진 FRAP data에 적용되었다. 서로 다른 온도에서 측정된 D_s 값들을 Arrhenius식에 적용하여 얻은 2차원 분자확산 활성화 에너지 값은, 문헌상에 보고된 stearic acid에 대한 값을 고려할 때, 적당하였다. The conventional fluorescence recovery after photobleaching (FRAP) models and analysis methods of experimental FRAP data have shown several limitations causing significant error. The goal of this study is to develop an improved FRAP model and analysis method. An improved model was determined to be Lardner's when experimental time after photobleaching (t) is less than 0.18τ_d and Soumpasis's when t is larger than that by plotting and comparing three conventional FRAP models. In addition, an improved analysis method running a computer program fabricated on the basis of error minimization algorithm was suggested and it allowed the lateral diffusion coefficient (D_s) and immobile fraction to be simultaneously obtained. This analysis method was applied to experimental FRAP data on Langmuir-Blodgett films confined between two silica surfaces. The activation energy resulted from the Arrhenius plot of the measured D_s at different temperature was reasonable considering that of stearic acid reported in the literature.

가속열화시험에 따른 케이블의 수명평가에 대한 신뢰성분석

정진동(Jin-Dong Jeong),이지연(Ji-Yeon Lee),강신동(Sin-Dong Kang),김재호(Jae-Ho Kim) 한국조명·전기설비학회 2020 조명·전기설비학회논문지 Vol.34 No.11

This paper comparatively analyzed the characteristics of the insulation resistance of TFR-8(Tray Frame Retardant power cable for fire service) cables according to accelerated degradation temperature and thermal stress application methods to ensure the validity of the accelerated degradation life test using the Arrhenius model. The study derived accelerated degradation times according to accelerated degradation temperatures by applying the Arrhenius model, and it manufactured cable specimens with equivalent lifetimes of 10, 20, 30, and 40 years using a forced-convection oven. The insulation resistance decreased as the temperature increased, and the measured insulation resistance of equivalent-lifetime cables were similar. The experimental results of constant thermal stress and step-stress application methods were also similar. These results verify the validity of the correlation between the Arrhenius model’s temperature and the chemical reaction rate. However, the accelerated degradation time could vary according to the calculation method of activation energy, which requires follow-up studies.

Remaining useful life estimation using accelerated degradation test, a gamma process, and the arrhenius model for nuclear power plants

강민구,Sunjae Lee,김종호,유찬세,장중순,Belachew Mekbibe Negatu,박상철 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

Predictive maintenance can be performed in nuclear power plants to prevent the failure of their components and equipment. Estimating the remaining useful life (RUL) of the components and equipment is the most important step in a predictive maintenance strategy. In this study, we focus on the RUL estimation of bipolar junction transistors (BJTs). We propose a practical method that applies a gamma process and the Arrhenius model and uses experimental data obtained by performing accelerated degradation tests (ADTs) at high temperatures. Using OriginLab, we chose the most suitable model as the degradation model. We calculated the parameter values of the proposed model using the gamma process and Arrhenius model. We estimated the RULs of BJTs using the proposed method.

Accurate Lifetime Estimation of Sub-20-nm NAND Flash Memory

Kyunghwan Lee,Myounggon Kang,Yuchul Hwang,Hyungcheol Shin IEEE 2016 IEEE transactions on electron devices Vol.63 No.2

<P>Previously, we developed a charge loss/gain model for NAND flash memory, which is taking into account various failure mechanisms. In addition, we extracted all the parameters of the new model in the highest (PV3) and lowest states (ERS). In this paper, however, the physical information for the parameters and the whole procedure of the parameter extraction are covered in detail. We also extracted the contribution rate (CR) of dominant mechanisms at the criterion of vertical bar Delta V-th_Total vertical bar according to the baking temperature. The results give the physical reason for abnormal retention behaviors such as apparent activation energy (E-aa) roll-off at the PV3 state and negative E-aa at the ERS state. Using the proposed method, we extracted the accurate lifetime at room temperature in all states (PV3, PV2, PV1, and ERS). A large gap was observed in the results of the lifetime estimation, which were extracted by the conventional Arrhenius model and the proposed model. Since the proposed model takes into account the retention characteristics for various mechanisms, this model provides a much more accurate prediction for the lifetime.</P>

자동차용 DC 모터의 브러시 마모 가속수명시험법 개발

엄학용(Hakyong Eom),김성옥(Sungok Kim),위신환(Shinhwan Wei),박상욱(Sangwook Park),김규로(Gyuro Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

In order to assess the reliability of the brush-type DC motor for automobiles, accelerated life test model and procedure are developed. By using this method, acceleration factor and life distribution are analyzed. The main results are as follows; ⅰ) the main acceleration factor of brush wear is voltage causing Joule heating effect. ⅱ) environmental temperature is a second factor to affect a brush wear failure. ⅲ) the life distribution of the auto-transmission control unit is fitted well to Weibull life distribution and the accelerated life model of brush is fitted well to the combination model of the Arrhenius’s model and the inverse power model. iv) activation energy is 0.2eV and exponent of the inverse power model is 8.49.