1,722,278 research outputs found
Kim Yu-hyun
No full text학위논문(석사)--아주대학교 일반대학원 :에너지시스템학과,2015. 2마그네슘 합금은 비강도가 높고 밀도가 낮아 알루미늄 합금을 대체하기 위한 소재로 주목 받고 있다. 하지만 마그네슘은 결정구조가 HCP 구조로 BCC, FCC의 결정구조를 가지는 타 금속에 비해 성형이 어려워 실적용에 어려움을 가지고 있다. 이러한 단점을 극복하기 위해 마그네슘에 합금원소를 넣거나 압출, 압연등의 가공을 통해 기계적 물성을 향상시키는 방법들이 연구되고 있다.
일반적으로 마그네슘 합금에 참가되는 원소는 기계적 강도와 성형성을 향상시켜주는 Al과 Zn이 많이 사용되며 상용금속으로 Al과 Zn이 첨가된 AZ계열 합금과 Zn과 Zr이 첨가된 ZK계열 합금이 많이 사용된다. AZ계열의 합금은 연신율이 좋아 성형성이 뛰어나지만 기계적 강도가 낮아 강도를 요하는 구조용 재료로 사용하기에 적합하지 않다. 하지만 ZK계열의 합금은 AZ계열보다 연신율은 낮지만 강도가 우수해 구조용재료로 주목받고 있다. 그래서 이번 연구에서는 ZK계열 마그네슘합금 중 강도와 연신율이 우수한 ZK60A합금(Mg-Zn-Zr)주조재를 사용했으며 가공법으로는 알루미늄을 비롯한 다양한 금속에서 적용되고 있는 압출가공법을 이용하였다.
실험변수는 압출공정에서 소재에 큰 영항을 미치는 압출비와 압출온도를 변수로 두고 진행했으며 실험조건은 압출비 6,10,15,24와 압출온도 200, 250, 300, 350℃ 지정하였다. 압출한 뒤 소재의 기계적 물성과 미세구조의 변화를 분석하기 위해 인장실험을 하여 인장강도와 연신율을 측정하였으며 미세조직은 FE-SEM에 달려있는 EBSD장비를 통해 결정립의 크기와 집합조직등을 관찰하였다. 기계적 물성의 경우 압출비가 클수록 온도가 낮을수록 강도는 향상되었으며 연신율의 경우는 압출비가 커질수록 향상되었으며 압출온도가 낮아질수록 감소되었다. 이러한 차이는 소재가 압출공정을 거치면서 미세구조가 변하는데 압출조건에 따라 미세구조변화의 차이가 기계적 물성에 영향을 미친다고 판단된다. EBSD결과를 살펴보면 압출비가 커질수록 결정립크기가 줄어들며 압출온도에 대한 영향은 미비한 것으로 보여진다. 압출온도가 낮아질수록 압출방향으로 연신된 결정립들이 생겨 연신율이 압출온도가 낮아질수록 하락하는 것으로 판단된다. 결정립크기의 편차가 크지 않은데에도 압출비나 압출온도에 따른 변화가 나타나는 것은 집합조직에 영향이 있다고 보여지며 실제로 실험결과에서도 압출온도가 낮을수록 압출방향으로 집합조직이 성장하며 이러한 방향성이 강도와 연신율에 영향을 주어 낮은 온도에서 강도가 향상되지만 연신율이 하락하는 경향을 보이게 된다.List of Text
국문요약 3
List of Figure 5
List of Table 7
1.서론 8
2. 배경이론 15
2.1 마그네슘합금의 특성 15
2.2 마그네슘합금의 첨가원소 18
2.3 마그네슘합금의 소성변형기구 20
2.3.1 슬립변형 20
2.3.2 쌍정변형 22
2.4 동적재결정(Dynamic recrystallization) 25
2.4.1 Bulging dynamic recrystallization 25
2.4.2 Continious dynamic recrystallization 25
2.4.3 Twin dynamic recrystallization 26
2.4.4 Low temperature dynamic recrystallization 26
2.5 집합조직 29
2.5.1 밀러지수 29
2.5.2 육방정계에서의 밀러지수 29
2.5.3 극점도(pole figure) 31
2.5.4 오일러각 33
2.6 압출공정 34
3. 실험방법 36
3.1 실험소재 36
3.2 전방압출 38
3.3 마이크로인장 40
3.4 미세조직분석 42
4. 실험결과 44
4.1 전방압출 44
4.2 압출비에 따른 전방압출 실험결과 45
4.2.1 압출비에 의한 기계적 물성변화 48
4.2.2 압출비에 의한 미세구조변화 50
4.3 압출온도에 따른 전방압출 실험결과 53
4.3.1 압출온도에 의한 기계적물성변화 53
4.3.2 압출온도에 의한 미세구조변화 55
4.4 압출비와 압출온도의 상관관계 58
5. 고찰 62
6. 참고문헌 64Maste
TRANSPOSISI PENERJEMAHAN NOVEL “땡볕” (TTAENGBYEOT) MENJADI “SENGAT MATAHARI” KARYA KIM YU JEONG
Full text linkPenelitian ini berfokus pada analisis transposisi yang terjadi pada novel “땡볕” (Ttaengbyeot) menjadi “Sengat Matahari” karya Kim Yu Jeong. Tujuan dari penelitian ini adalah untuk mengetahui jenis transposisi apa saja yang terdapat dalam novel “땡볕” (Ttaengbyeot) menjadi “Sengat Matahari” karya Kim Yu Jeong dan pengaruh transposisi. Berangkat dari pentingnya penerjemahan yang baik, peneliti mengangkat salah satu teknik penerjemahan yaitu transposisi untuk diteliti. Penelitian ini menggunakan metode deskriptif kualitatif. Data yang digunakan adalah transposisi yang terdapat dalam novel “땡볕” (Ttaengbyeot) karya Kim Yu Jeong beserta terjemahannya. Analisis dilakukan berdasarkan teori Catford dengan cara mengumpulkan data, mengklasifkasi data sesuai dengan jenisnya, mereduksi data, dan memberikan penjelasan. Hasil yang ditemukan yaitu sebanyak 179 data transposisi yang terdiri dari 7 data pergeseran tataran, 81 data pergeseran struktur, 17 data pergeseran kelas, 70 data pergeseran unit, 4 data pergeseran intrasistem, dan pengaruh transposisi pada terjemahan. Dari hasil analisis, diperoleh kesimpulan transposisi yang paling banyak ditemukan adalah pergeseran struktur yang menunjukkan bahwa struktur bahasa Indonesia dan bahasa Korea cukup berbeda sehingga diperlukannya transposisi saat penerjemahan.
This research primarily focuses on analyzing the transposition that occurred in the novel "땡볕" (Ttaengbyeot) to "Sengat Matahari" by Kim Yu Jeong. The purpose of this research is to find out what types of transpositions that are contained in the novel “땡볕” (Ttaengbyeot) to Kim Yu Jeong's “Sengat Matahari” and the effects of the transposition. From the importance of a good translation, the researcher raised one of the translation techniques, and that is a transposition studies. This research used a descriptive qualitative method. The data used are the transpositions contained in the novel "땡볕" (Ttaengbyeot) by Kim Yu Jeong and its translation. The analysis is done based on the Catford theory by collecting the data, classifying the data according to its type, reducing the data, and providing explanations. The results found were 179 data transpositions consists of 7 data of level shifts, 81 data of structure shifts, 17 data of class shifts, 70 data of unit shifts, 4 data of intrasystem shifts, and the effect of transpositions on translation. From the analysis, the conclusion is that the most transpositions to be found are the structure shift that indicates the structure of Indonesian language and Korean language is quite different therefore transposition is needed during translation
[Numbered accounts at Swiss banks and justice in tax affairs : are tax revenue services allowed to use illegaly acquired data on taxpayers?
No full textby Kim Yu ChanIn korean language. - Electronic ed.: Seoul ; Bonn : FES, 2010
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Why do(n't) young people watch the Olympics?: A comparison of motives and constraints for attendance and media viewing
No full textThis study investigates internal and external motives, and intrapersonal, interpersonal, and structural constraints affecting domestic young peoples intentions for attending or media viewing the 2018 PyeongChang Winter Olympics. Through thought-listing, key motives and constraints are identified. Based on surveys and SEM analysis, relationships among motives, constraints, and intentions are tested, and findings related to attendance and media viewing are compared. Perceived motives/constraints/intentions in host and non-host regions are compared based on mean structure analysis. Universal (e.g., curiosity, enjoyment, social influence) and contextual (e.g., lack of knowledge, cost) motives/constraints affecting attendance and/or media viewing are identified. Interestingly, only structural constraints affect attendance intention, whereas intra- and interpersonal constraints affect media viewing intention as well. Perceived levels of motives/constraints/intentions partially vary between host and non-host regions. Diversified marketing strategies for Olympics attendance and media viewing in host- and non-host regions are discussed. Copyright © 2021 Inderscience Enterprises Ltd.N
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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