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

Shear Stress Analysis of a Polypyrrole/Clay Nanocomposite-based Electrorheological Fluid(Note)

Fei Fei Fang,Hyoung Jin Choi 한국공업화학회 2006 Journal of Industrial and Engineering Chemistry Vol.12 No.6

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.

Numerical Simulation of Semi-blunt Puncture Behaviors of Woven Fabrics Based on the Finite Element Method

Fei-Fei Wang,Yan-Li Ma,Lan Xu,Ping Wang,Yan Zhang 한국섬유공학회 2018 Fibers and polymers Vol.19 No.11

This paper focuses on the semi-blunt puncture behavior of woven fabrics via finite element analysis (FEA) approaches. In these finite element (FE) models, main structure parameters, such as weave structure, warp density as well as friction coefficient, are systematically considered and calculated via FEA. These microstructure geometrical models are builtup with full consideration of interaction between warp and weft yarns. The theoretical results show that plain woven fabric has better puncture resistance compared with 2/1 twill and 5-harness satin fabrics. With the increase of warp density and friction coefficient, the puncture property of woven fabric will be dramatically improved. Finally, an energy consumption method is adopted to analyze the puncture damage process of woven fabric. The simulation results will benefit for the optimum design of woven fabric with excellent puncture performance.

Preparation and Properties of WS₂/Co<SUB>9</SUB>S<SUB>8</SUB> Core-shell Nanocrystals@Hollow-porous Carbon Fiber (HCF) for Water Electrolysis

Fei-fei Wang,Ping Wang,Ick Soo Kim 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2

Developing highly-efficiency, cost-effective, high-throughput and durable bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is of paramount important for water electrolysis. Herein, we report an economical method for the synthesis of WS₂, Co9S8 and WS₂/Co9S8 nanocrystals with different diamension, structure and morphology grown on hollowporous carbon fiber (HCF) via calcination and S vapor inducing reaction treatment as bifunctional catalysts for water electrolysis. Then, the effects of structure and morphology on the water electrolysis of WS₂ and (or) Co9S8@hollow-porous carbon fiber (HCF) were investigated. The catalyst W₁Co₁S@HCF with W/Co molar ratio of 1:1 presented excellent HER activity for 228 ± 8.38 mV overpotential at a current density of 10 mA/cm² with the Tafel slope of 111 mV/dec. More importantly, the W1Co1S@HCF had superior stability in acidic electrolyte solution. The catalyst W₁Co₃S@HCF with W/Co molar ratio of 1:3 gained excellent OER activity for 437 ± 19.47 mV overpotential at a current density of 10 mA/cm² with the Tafel slope of 99 mV/dec. The excellent electrocatalytic actives can be attributed to the synergetic effects of appropriate molar ratio WS₂/Co9S8 core-shell and hollow-porous structure in addition to providing more potential implantation sites.

Preparation of oral nanoemulsion drug delivery system loaded with punicalagin: in vitro antibacterial activity, drug release, and cell safety studies

Fei‑Fei Shi,Yu‑Juan Mao,Ying Wang,Hai‑Feng Yang 한국고분자학회 2024 Macromolecular Research Vol.32 No.3

The objective of the present study was to develop a W/O/W nanoemulsion (NE) drug delivery system loaded with punicalagin (PGN) for oral delivery and evaluate its potential in antibacterial therapy. The W/O/W PGN-NE was prepared using a two-step process by combining ultrasonic with high-energy emulsification and subsequently characterized by its droplet size, zeta potential, and morphology. The PGN-NE was further evaluated for its pH, in vitro antibacterial activity, drug release property, and cytotoxicity. The results indicated the formation of spherical, nano-sized globules of PGN-NE had a mean particle size of 45.53 ± 2.2 nm, with a PDI value of 0.22 ± 0.028, zeta potential was −4.67 ± 0.88 mV, and pH value was 5.8. In vitro antibacterial activity studies showed a significantly higher antibacterial activity of PGN-NE in comparison to free PGN, suggesting that NE can effectively improve the antibacterial effect of natural pharmaceuticals. The drug release assay demonstrated that PGN was slowly released from the NE preparation and absorbed, helping to prolong the potency and improve the bioavailability of PGN. Cytotoxicity testing showed that PGN had reduced toxicity when encapsulated in NE. Thus, the developed NE formulation of PNG exhibited a greater potential for the slow-release effect delivery and in the treatment of microbial infections with favorable safety profile.

Electrorheological characteristics of conducting polypyrrole/swollen MCM-41 nanocomposite

Fei Fei Fang,Min Seong Cho,Sang Soon Yoon,안화승,최형진 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.1

Nanocomposite of mesoporous swollen MCM-41 (S-MCM-41) with conducting polypyrrole (PPY) (PPY/S-MCM-41) conned insidedispersed in silicone oil were examined under an applied electric eld. N2-adsorption isotherm and XRD analysis were employed to conrmsuccessful insertion of the PPY chain into host channels of the S-MCM-41. ER responses of the nanocomposite based ER uid wereinvestigated using a rotational rheometer, showing typical ER characteristics of the increment of shear stress as a function of an applied electriceld strength.# 2007 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.