Behavior and Mechanism of Void Welding Under Thermal Mechanical Coupling

Fei Chen,Xitao Wang,Huiqin Chen,Shue Dang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

Shrinkage cavity, microporosity, blowhole and the likes are the typical void defects in ingot. Only through reasonable hightemperature deformation and heat preservation process can the void defects be closed and welded to ensure the high qualityof forgings. However, there are few researches on the welding behavior of voids, and the understanding of the void weldingmechanism is still insufficient. In order to further study the welding behavior of void and explore the welding mechanism,the welding process of void and microstructure evolution around void under thermal mechanical coupling were studied byphysical simulation. The results show that heating temperature, holding time, plastic deformation play an important role invoid welding. The void welding degree increases with the increase of heating temperature, holding time and plastic deformation. Besides, there are three main welding mechanisms for void defects, including the volume of microvoids decreasesdue to vacancy diffusion, the void welding mechanism caused by the austenite-ferrite transformation at lower temperaturesand the void welding mechanism caused by recrystallization and grain growth of austenite grains at higher temperatures.

High‑Temperature Deformation Behavior of MnS in 1215MS Steel

Fei‑Ya Huang,Yen‑Hao Frank Su,Jui‑Chao Kuo 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6

The effect of manganese sulfide (MnS) inclusions on the machinability of free-cutting steel is based on their morphology,size and distribution. Furthermore, the plasticity of MnS is high during the hot working caused different characterizationof MnS. In this study, the deformation behavior of MnS in 1215MS steel after a thermomechanical process was investigatedat 1323 K. The microstructures of MnS inclusions were characterized by optical microscopy, scanning electronmicroscopy, energy-dispersive spectrometry, and electron backscattering diffraction (EBSD). As the thickness reductionof the inclusions increased from 10 to 70%, their average aspect ratio increased from 1.20 to 2.39. In addition, the deformabilityof MnS inclusions was lower than that of the matrix. The possible slip systems of A, B, C, and D plane traces werē10̄1̄101 , 10̄ 1 [101], (011) 01̄ 1 , and (110) 1̄10 . Furthermore, the EBSD measurements suggested that slip planes inMnS inclusions occur on {110} planes.

중국인 학습자의 보조사 ‘만, 밖에, 뿐’의 사용 양상 연구

정비 ( Ding¸ Fei ) 인하대학교 교육연구소 2020 교육문화연구 Vol.26 No.4

본 연구는 중국인 학습자가 한국어 보조사 ‘만, 밖에, 뿐’의 통사적, 의미적 기능을 정확하게 습득하는지, 보조사 ‘만, 밖에, 뿐’을 습득할 때 어려운 점이 무엇인지 등을 파악하기 위해 학습자 실제 언어 자료로 구축된 학습자 말뭉치를 이용해 중국인 학습자의 한국어 보조사 ‘만, 밖에, 뿐’의 사용 양상을 밝혀내는 것을 목적으로 하였다. 이를 위해 본 연구는 우선 형태 분석된 중국인 학습자의 문어 말뭉치에서 보조사 ‘만, 밖에, 뿐’의 용례를 추출하고, 각 보조사의 사용 빈도 및 선행성분과 후행성분의 분포 양상을 전면적으로 검토하였다. 그 다음으로 중국인 학습자의 보조사 ‘만, 밖에, 뿐’의 오류를 분류하여 특징과 원인을 파악하였다. 마지막으로 교수·학습 상 주의해야 할 점을 제시하였다. 분석 결과 보조사 ‘만, 밖에, 뿐’ 앞에 명사구가 가장 많이 출현하였고, 그 다음으로는 조사와 주로 결합하였다. 어미와 기타 성분일 경우에는 주로 ‘만’과 결합하는 것으로 나타났다. 후행성분은 주로 조사와 결합하였고, ‘만’ 뒤에 출현하는 조사는 다양한 반면에 ‘밖에’와 ‘뿐’은 상대적으로 단순하게 나타났다. 중국인 학습자의 보조사 ‘만, 밖에, 뿐’의 오류는 생략, 대치, 첨가, 형태, 기타로 분류하여 오류율과 특징을 밝히었다. 이에 향후 중국인을 대상으로 하는 보조사 ‘만, 밖에, 뿐’의 교육에 대해 제언하였다. The purpose of this study was to identify the usage pattern of the Korean language auxiliary particles ‘만, 밖에, 뿐' by Chinese learners using the Learners' corpus, which is based on the learners' actual language materials, to find out whether Chinese learners correctly acquire the syntactic and semantic functions of the Korean auxiliary particles ‘만, 밖에, 뿐' and to identify the difficulties in acquiring the auxiliary particles ‘만, 밖에, 뿐'. To this end, this study first extracted the examples of auxiliary particles ‘만, 밖에, 뿐' from the form-analyzed learners' corpus, and reviewed the frequency of use and distribution of leading and trailing components of each assistant in full. Next, the characteristics and causes of the errors of the Chinese learners' auxiliary particles ‘만, 밖에, 뿐' were identified by classifying them. Finally, we presented some points of caution in teaching and learning. The results of analysis indicate that nouns appeared most frequently in front of the auxiliary particles ‘만, 밖에, 뿐'. The trailing component was mainly combined with the investigation. The errors of the Chinese learners' auxiliary particles ‘만, 밖에, 뿐' were classified into omission, substitution, addition, form and other, revealing the error rate and characteristics. In response, it suggested the education of his auxiliary particles ‘만, 밖에, 뿐' for Korean learners of Chinese.

Interview with Professor Fei-Ling Wang, author of The China Order: Centralia, World Empire, and the Nature of Chinese Power (2017)

Jaewoo Choo(토론자),Fei-Ling Wang(토론자) 동북아역사재단 2017 Journal of Northeast Asian History Vol.14 No.2

퍼지를 이용한 연료전지 시스템의 온도제어

Fei-Fei Qin,Ya-Xiong Wang,Young-Bae Kim 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-

고분자 전해질 연료전지의 열관리는 연료전지 작업 효율을 향상시키고 수명을 연장시키기는 매우 중요한 역할을 한다. 스택 온도가 너무 낮으면 전기 화학 반응의 속도가 늦어지고 반응에 의해 생성되는 물의 증발을 방해 한다. 그러나, 너무 높으면 온도는 촉매 낭비, 열 손실, 폐기물 방출 등 연료 전지의 수명을 줄인다. 본 논문은 고분자 전해질 연료전지(PEMFC) 열 관리를 위한 연구이다. 우선, 연료전지의 열역학 이론에 기초하여, MATLAB / Simulink를 통해 연료전지의 동적 모델을 만들었다. 실험을 통해 수학적인 시뮬레이션 모델링을 검증했다. PEMFC 동적 모델에 기초하여, 본 연구는 퍼지 논리 전략을 통하여 열 관리 제어 시스템을 설계 하였다. 이상적인 온도(PEMFC 효율 최적의 온도 곡선)와 스택 실제 온도의 오차, 그 오차의 미분 항, 및 외부 간섭 조건 전류(PEMFC 현재 스택)로 퍼지 제어기의 입력으로 구성 되었으며, 제어기의 출력은 냉각 팬의 제어전압이다. 본 연구는 열 관리를 위한 처음으로 외부 간섭 조전, 즉, 스택 전류를 제어기에 도입하여 복잡한 한 퍼지 제어기를 만들었다. 3차원 퍼지 제어기는 간단한 퍼지 제어기를 통해 발생한 정적 오류를 줄일 수 있다. 뿐만 아니라 제어 최적화 성능을 향상시켰다. 퍼지 논리 제어방법을 통해 연료전지 열 관리를 빠른 응답 시간과 작은 오차의 오버 슈트를 얻을 수 있다. 즉, 더 효율적으로 제어 성능을 향상시켰다.

Information Security in the Age of Algorithms

Fei Yang(Fei Yang),Xuan Luo(Xuan Luo) 아시아사회과학학회 2023 Jornal of Asia Social Science Vol.10 No.1

Algorithms are now widely used in all areas of social life, building a new social picture and reality. As a technology based on big data modelling and analysis, algorithms are embedded in all aspects of information production and distribution by means of technology, and become an important force in the construction of information environment. Under the algorithmic logic of information dissemination, the visible and invisible are in fact influenced by the algorithm as an authoritative mediator and mediator. From Daniel Dayan's 'visibility' perspective, this paper examines the risks posed by algorithms in three areas: the risk of passive disclosure of personal privacy, the use and control of personal data by profit-seeking algorithms, and the polarisation of information cocoons and circles. The information security risk brought by algorithms is attempted to be tackled and improved from several aspects, such as constructing a 'trinity' information security strategy system; adhering to the mainstream value orientation and highlighting the rational balance of “tool-value” of algorithms; and bringing into play multiple mechanisms together with effects.

Prevalence and Risk Factors of Cerebral Small Vessel Disease in a Chinese Population-Based Sample

Fei Han,Fei-Fei Zhai,Quan Wang,Li-Xin Zhou,Jun Ni,Ming Yao,Ming-Li Li,Shu-Yang Zhang,Li-Ying Cui,Zheng-Yu Jin,Yi-Cheng Zhu 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.2

Background and Purpose Epidemiological data of cerebral small vessel disease (CSVD) in the general population of China are lacking. We report on the prevalence of lacunes, white matter hyperintensity (WMH), and cerebral microbleeds (CMBs) in a community-based sample in China and compare the results with those of other studies. Methods This was a cross-sectional analysis of the population-based Shunyi Study in China. A total of 1,211 stroke-free participants (mean age, 55.6±9.3 years; 37.4% men) with available 3 Tesla (3T) magnetic resonance images were included in this analysis. Demographic information and risk factor data were assessed. The overall and age-specific prevalence of lacunes, WMH, and CMBs was evaluated. Associations between cardiovascular risk factors and the presence of these lesions were analyzed by multiple logistic regression. Results Our study showed a prevalence of 14.5% for lacunes, 72.1% for periventricular hyperintensity (PVH), 65.4% for deep white matter hyperintensity (DWMH), and 10.6% for CMBs. When compared with other community-based samples, individuals in the same age group showed a higher burden of lacunes and a relatively lower prevalence of CMBs. Advanced age was independently associated with the prevalence of these CSVD markers, while the presence of hypertension increased the risk of lacunes, PVH/DWMH, and CMBs in deep or infratentorial locations. Conclusions A higher burden of lacunes but a relatively lower prevalence of CMBs was observed in this Chinese population. This notable result highlights the challenge of CSVD prevention in China. Chinese have a risk factor profile for CSVD similar to those in other populations.

Organic/inorganic hybrid of polyaniline/BaTiO₃ composites and their electrorheological and dielectric characteristics

Fei Fang, Fei,Hye Kim, Ji,Jin Choi, Hyoung,Seo, Yongsok Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.105 No.4

<P>Barium titanate (BaTiO<SUB>3</SUB>) inorganic particles which possess large electronic resistance and excellent dielectric properties were employed to synthesize conducting polyaniline (PANI)/BaTiO<SUB>3</SUB> composites via an in situ oxidative polymerization, since conducting PANI/inorganic composites have been considered as a superior candidate of electrorheological (ER) fluids because of their physical properties, unique structure, and the combined merits of the two phases. The influence of the fraction of BaTiO<SUB>3</SUB> particles in the as-synthesized composites on the physical properties (morphology and crystal structure) and the ER behaviors were examined. Yield stress data obtained were analyzed based on the universal yield stress equation as a function of applied electric field and it was found that the universal yield stress equation collapses these data onto a single curve independent of BaTiO<SUB>3</SUB> particle concentration. Their shear stresses under an applied electric field were also found to be fitted well with the Cho–Choi–Jhon model. In addition, the investigated dielectric spectra were found to be useful to interpret the differences in the ER performances for the PANI/BaTiO<SUB>3</SUB> composite based ER fluids. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007</P>

Electrorheologically Intelligent Polyaniline and Its Composites

Fei Fei Fang,이보미,최형진 한국고분자학회 2010 Macromolecular Research Vol.18 No.2

Electrorheological (ER) fluids are generally composed of electrically polarizable inorganic or organic particles dispersed in insulating oils. These materials are intelligent/smart materials in that they are capable of changing their state from liquid-like to solid-like very quickly under an applied electric field. This feature article reviews the literature regarding the fabrication of conducting polyaniline (PANI) and PANI composite particles,their ER performance, as well as their chemical and physical characteristics of morphology and crystal structure. The ER behavior of these intelligent materials was also analyzed using a range of rheological equations of state and their dielectric properties.

On Quantifying Global Warming Sensitivity and El Niño-Southern Oscillation Criticality

Fei-Fei Jin 한국기상학회 2023 한국기상학회 학술대회 논문집 Vol.2023 No.4