Influence of Microstructure and Mechanical Properties on Formability in High Strain Rate Rolled AZ31 Magnesium Alloy Sheets

Fubao Liu,Xiao Liu,Biwu Zhu,Hui Yang,Gang Xiao,Mingyue Hu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

High strain-rate rolling (≥ 10 s−1) has been successfully employed to produce AZ31 magnesium alloy sheets to a high reductionof 82% with a fine grain structure in a single pass. The rolled sheets inevitably undertake various forming processessuch as press and deep forming in the fabrication stage. To investigate the formability, the Erichsen tests were carried out onhigh strain rate rolled AZ31 magnesium alloy sheets at room temperature. The relationship among mechanical properties,microstructure and formability were investigated. The crack behavior during Erichsen tests was also studied. It was foundthat the formability was related to the lowest in-plane tensile strengthen and dislocation density of initial microstructure. The competitive relationship between micro-crack and twinning/shear bands would also influence the formability of highstrain rate rolled magnesium alloy sheets. Deformed shear band with substaintial twins prohibits the crack extension andenhances strengthen of materials in front of crack tip.

The generalized Fermat type difference equations

Kai Liu,Lei Ma,Xiaoyang Zhai 대한수학회 2018 대한수학회보 Vol.55 No.6

This paper is to consider the generalized Fermat difference equations with different types which ever considered by Li \cite{li}, Ishizaki and Korhonen \cite{IK}, Zhang \cite{zhangjie} and Liu \cite{liuk4,11,1177,liu}, respectively. Some new observations and results on these equations will be given.

Rainfall-induced Landslide Hazard Analysis Based on GIS in Yanbian Region, China

Liu,Xiu Xuan,Quan, He Chun,이병걸 대한공간정보학회 2017 대한공간정보학회지 Vol.25 No.4

This paper mainly studies landslide hazard in Yanbian region,8 landslide factors of soil moisture content, hydrogeology, land use type, slope, slope aspect, fault, river and rainfall are analyzed in the area of Yanbian region. Using the analytic hierarchy process (AHP), the relative weights of 8 landslide factors were obtained, and the internal weights of each factor were determined by the data; the rainfall factors were then divided into three categories such as average annual rainfall, average flood season rainfall, and the maximum average rainfall. And the comparison of the rainfall factors was made. Finally based on the results of these weights to the remote sensing technology(RS) and geographic information system(GIS) technology combined to evaluate its area, we are mapping the risk assessment area for landslide hazard in Yanbian region. According to the map analysis, figure in the dangerous hierarchies result in accordance with the historical landslides is better. At the same time. landslides and hazard area of statistical data analysis showed that the AHP method combined with GIS technology is suitable for promoting the Yanbian regional landslide hazard assessment.

반의 공기(共現) 사자격 성어의 구조 형식에 대한 연구

LIULIU 한국중국어교육학회 2022 중국어교육과연구 Vol.- No.37

본고는 『成語大詞典』에 수록된 반의 공기 연합형 사자격 성어 730개를 연구 대상으로 내부 조어 형태소의 품사 결합 구조를 고찰하고, 분류하였다. 그 결과, 연합형 사자격 성어의 내부 조어 형태소 품사 결합 구조는 모두 43개 유형이며 주로 ‘동+명·동+명’, ‘명+동·명+동’ 구조이다. 이는 ‘動賓구조’와 ‘主謂구조’가 중국어에서 가장 기본적인 통사 유형이기 때문인 것으로 판단된다. 다음으로, 반의 공기 연합형 사자격 성어의 품사 결합 구조 중, ‘實詞+實詞’ 결합 구조가 가장 많다. 또한, 품사 결합 구조 중 대칭 결합 구조의 성어 수가 제일 많다. 이는 연합형 사자격 성어의 전후 두 부분의 구조가 같고 품사는 같거나 다른 특징을 가지고 있기 때문이라고 볼 수 있다. 이 밖에도 반의 공기 연합형 사자격 성어에서는 내부 조어 형태소의 품사 변화가 발생하여, 임시적으로 다른 품사의 통사적 기능을 수행하는 경우가 빈번히 나타난다. 이에 후속 연구를 위하여 기초자료를 제공할 수 있다.

중국인 학습자를 위한 담화표지 ‘어디’에 대한 연구 - 한·중 화용 기능의 대조를 중심으로 -

LIUNA 한국국어교육학회 2015 새국어교육 Vol.0 No.103

Korean interrogative ‘eodi’ has developed rich meanings and conversational functions during the process of grammaticalization. It presents Chinese learners with many difficulties in understanding and using ‘eodi’ properly. In this study the preceding studies on the functions of ‘eodi’ were examined and a new classification system was established. To help learners to get an overall comprehension about the usage of discourse marker ‘eodi’, various pragmatic functions of ‘eodi’ were analysed from the comparative viewpoint with Chinese. Then, some problems with descriptions of ‘eodi’ in Korean textbooks were also discussed. Lastly, from the educational perspective, some appropriate methods of sequential presentation in Korean textbooks and education for Chinese learners were suggested based on the results of CA(comparative analysis). 한국어 의문사 ‘어디’는 문법화의 과정을 거쳐 의문 기능을 제외한 여러 화용 기능을 가지게 되면서 담화표지로 변신한다. ‘어디’는 담화표지로서의 용법이 매우 다양할 뿐만 아니라 중국어와 대응 관계도 복잡하여 중국인 학습자들에게 매우 어려운 학습 내용으로 인식되고 있다. 본 연구에서는 한국어 화용 교육을 위한 입장에서 기존 연구에 의해 밝혀진 ‘어디’의 화용 기능을 재검토하여 체계화시켜 중국어 해당 표현과의 대조 분석을 시도하였다. 이는 ‘어디’가 맥락에서 나타내는 특수한 담화 효과에 대한 중국인 학습자의 이해를 확보시키기 위해서이다. 이어서 현행 한국어교재에서 ‘어디’의 제시 양상에 대한 고찰을 통해 문제점을 짚어보았다. 또한 학습자의 화용 능력을 향상시키기 위해 ‘어디’의 제반 화용 기능을 교재에 적극적으로 반영해야 한다고 주장하면서 한국어교육에의 적용 방법을 모색해 보았다.

並列式叠加介词的语义形成機制考察

LIUYUN,김현철 중국어문학연구회 2018 중국어문학논집 Vol.0 No.109

The morphological reduplication of prepositions is synchronic, prescribing the combination of morphemes on the basis of word-formation rules. However, as for conditions in which reduplications make sense, semantics which are appropriate and causes which have led to the formation of syntaxes, the lexical diachronic evolution and development have the final say. This paper adopted the source-tracing approach to investigate “自, 从, 打, 由” and their respective reduplicated phrases in terms of the following three steps: semantic evolution, semantic models and reduplicated mechanisms. Firstly, it had adopted the method of reanalysis and grammatical path to parse the semantic evolutions of the four monosyllabic prepositions and how the derivational senses generated as well as how the implied semantic features embodied themselves on the syntactic level. Second, based on a full understanding of monosyllables and semantic features and functions of reduplicated preposition, it re-categorized the propositions and their corresponding features and unearthed the relations between semantic coverages and semantic features, which involved mutual selection, blending and reduplication.

Facile preparation and characterization of poly(vinyl alcohol)/chitosan/graphene oxide biocomposite nanofibers

LIUYANAN,박미라,신혜경,PANTBISHWESHWAR,최재운,박용완,이준엽,박수진,김학용 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

Poly(vinyl alcohol) (PVA)/chitosan (CS)/graphene oxide (GO) biocomposite nanofibers have beensuccessfully prepared using aqueous solution by electrospinning. CS colloidal gel in 1% acetic acid can bechanged to homogeneous solution by using electron beam irradiation (EBI). The uniform distributions ofGO sheets in the nanofibers were investigated by field emission scanning electron microscopy (FESEM)and Raman spectroscopy. FESEM images illustrated that the spread single GO sheet embedding intonanofibers was formed via self-assembly of GO sheet and PVA/CS chains. And the average diameters ofthe biocomposite nanofibers decreased (200, 173, 160 and 123 nm) with increasing the contents of GO(0.05, 0.2, 0.4 and 0.6 wt%). Raman spectra verified the presence of GO in the biocomposite nanofibrousmats. The mechanical properties of as-prepared materials related with GO contents. It revealed that thehighest tensile strength was 2.78 MPa, which was 25% higher than that of neat PVA/CS nanofibers. Antibacterial test demonstrated that the addition of GO to PVA/CS nanofiber had great ability to increaseinhibition zone till 8.6 mm. Overall, these features of PVA/CS/GO nanofibers which were prepared byeco-friendly solvent can be a promising candidate material in tissue engineering, wound healing anddrug delivery system.

장용학 소설의 역사인식 연구

LIUJINGZI 동국대학교 한국문학연구소 2015 한국문학연구 Vol.0 No.49

In the novels of Yonghak Chang, he engages in his criticism of reality and historical-philosophical quest. He intends to view ‘history’ from a holistic perspective and his interest in ‘reevaluation of history’ leads to ‘rewriting of history’ in his late years. This paper aims to examine the historical awareness of Chang based on his novels. He deals with all the historical issues while he continues the criticism of reality and historical- philosophical quest in his Korean war-based novels. Chang concludes that Korean war is a ‘misjudgement in the history of mankind’ and history is the ‘repetition of excitement and cooling down’, assuming a certain world to come in the future. In his novels against the backdrop of Korea’s modernization, Chang diagnoses that it is almost impossible to demand democratization in Korean society and concludes that the history written by the power holder is only a record regardless of whether it is true or not. In the novels with the background of Japanese colonial era, he criticizes the Japanese attitude of distorting history. He also claims that the study of history should be focused on literature analysis, highlighting problems of Japanese historians’ interpretation of history. Then history remains only ‘fictional composition’ and it exists as a ‘narration’. 장용학은 현실비판과 함께 역사철학적인 탐구를 소설로 담아내었다. 그는 ‘역사’를 총체적으로 바라보고자 하였으며, ‘역사 다시보기’에 대한 관심이 후기에 이르러서는 ‘역사 다시쓰기’의 실제 작업으로 이어진다. 본고는 장용학 소설에 나타난 역사인식을 고찰하는 것을 목표로 하였다. 6․25전쟁을 배경으로 하는 소설에서는 현실비판과 함께 끊임없는 탐구를 지속하면서 역사의 제반 문제에 대한 성찰을 드러내었다. 이때 장용학은 한국전쟁이 ‘인류사의 오산’이라고 판정 내리며, ‘흥분과 냉각의 되풀이’가 역사라는 결론을 얻게 되고 어떤 미래의 세상을 상정하고 있다. 근대화 과정을 배경으로 하는 작품에서는 한국사회에서 민주주의를 요구하는 것은 거의 불가능하다고 판단하였으며, 이때 집권자에 의해 쓰인 역사는 그 진실 여부를 떠나 하나의 기록임에 불과하다는 결론을 얻게 된다. 일제시대를 배경으로 하는 작품에서는 역사를 왜곡하는 일본의 역사서술태도에 대해 비판한다. 또한 일본 역사가들의 역사해석에 나타난 여러 가지 문제점들을 밝히면서 역사연구는 문헌분석에 집중되어야 한다고 주장한다. 이때 역사란 곧 ‘허구적 구성물’에 지나지 않으며, 하나의 ‘서사’로서 존재하게 된다.

중국인 학습자를 위한 한국어 담화표지교육 내용 구성에 대한 일고찰

LIUNA 국제한국언어문화학회 2014 한국언어문화학 Vol.11 No.3

Discourse markers haverich conversational functions along with the variation of meanings inspoken language. This phenomenon is concerned to grammaticalization. This study is about the contents construction of Korean discourse markerseducation and aims to select discourse markers that are suitable forintermediate and advanced Chinese students to learn. First, some primarydiscourse markers that are addressed in preceding studies from theperspective of Korean language education (KLE) will be selected. Thenaccording to the selection criteria for Chinese learners, the ultimateeducational contents will be given out.

現代漢語“把/被…給”的語義疊加及句法形成機制考察

LIUYUN 중국어문학연구회 2017 중국어문학논집 Vol.0 No.107

This paper investigates the form “ba/bei…gei VP” in contemporary Chinese language, which is endowed with many particularities. Firstly, this paper analyzes the overlap principle of the internal semantics of the form “ba/bei … gei VP” from the perspectives of semantic overlap and syntactic integration. The semantics of this form includes two categories of semantic overlap, “semantic overlap of similar meanings” and “semantic overlap of opposite meanings”. This form is also strengthened pragmatically due to the semantic overlap. on this question and idea. Second, this paper discusses from the syntactic point of view the type and characteristics of the VP in this form, and the characteristics of the negation form and other derived forms of it. Finally, the paper then goes on to investigate the syntactic generation of “ba/bei…gei VP” from the perspectives of semantics and generative syntax. It is believed that “ba/bei…gei VP” is derived from “NP gei VP” and “gei NP VP” through semantic and syntactic evolution. Since “gei” in sentences plays the role of introducing implicit arguments, when an argument is added, “ba” and “bei” are thus needed to mark and introduce the new argument. The form is in turn further extended and the “ba/bei … gei VP” form therefore takes the shape.