Microstructure, Tensile and Fatigue Properties of Al–5 wt.%Mg Alloy Manufactured by Twin Roll Strip Casting

Joon‑Young Heo,Min‑Seok Baek,Kwang‑Jun Euh,Kee‑Ahn Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

This study investigated the microstructure, tensile and fatigue properties of Al–5 wt.%Mg alloy manufactured by twin rollstrip casting. Strips cast as a fabricated (F) specimen and a specimen heat treated (O) at 400 °C/5 h were produced andcompared. In the F specimen, microstructural observation discovered clustered precipitates in the center area, while in theO specimen precipitates were relatively more evenly distributed. Al, Al 6 (Mn, Fe), Mg 2 Al 3 and Mg 2 Si phases were observed. However, most of the Mg 2 Al 3 phase in the heat-treated O specimen was dissolved. A room temperature tensile test measuredyield strength of 177.7 MPa, ultimate tensile strength of 286.1 MPa and elongation of 11.1% in the F specimen and167.7 MPa (YS), 301.5 MPa (UTS) and 24.6% (EL) in the O specimen. A high cycle fatigue test measured a fatigue limit of145 MPa in the F specimen and 165 MPa in the O specimen, and the O specimen achieved greater fatigue properties in allfatigue stress conditions. The tensile and fatigue fracture surfaces of the above-mentioned specimens were observed, and thisstudy attempted to investigate the tensile and fatigue deformation behavior of strip cast Al–5 wt.%Mg based on the fi ndings.

담배의 잎조직 배양에 있어서 기관형성과 동위효소 유형에 미치는 생장조절제의 영향

成淳基,金濬喆,成敏雄 慶尙大學校 1986 論文集 Vol.25 No.2

담배(N. tabacum cv. NC 2326) 잎조직 배양에서 기관형성에 가장 효과적인 생장조절제의 배지조성을 찾기위하여 NAA와 kinetin의 농도별 혼합처리 5종류 및 picloram과 BAP의 농도별 혼합처리 5종류의 배지에서 26℃ 조건으로 35일간 잎조직을 배양시켜 각 처리구에 대한 기관형성률을 조사하고, 6종류의 효소에 대한 동위효소 유형 및 단백질 함량은 기관형성이 가장 잘된 0.01㎎/l pocloram+0.6㎎/lBAP 처리구와 0.5㎎/l NAA+0.5㎎/l kinetin 처리구의 두 처리구의 배양체를 대상으로 조사한 결과는 다음과 같다. 1. NAA와 kinetin을 혼합처리한 5종류의 배지중 0.5㎎/l+0.5㎎/l kinetin 처리구에서 shoot와 뿌리가 각각 100% 및 50%로서 가장 높은 기관형성률을 나타냈다. picloram과 BAP 혼합처리구에서 callus형성률은 평균 6%로 callus 형성에는 효과적인 배지는 아니었으나 기관형성률은 높게 나타났다. 그 중 0.01㎎/l pocloram+0.5㎎/lBAP 처리구에서 shoot와 뿌리가 각각 100% 및 90%의 형성률을 나타내어 기관형성에 가장 효과적이었다. multiple shoot 형성에는 picloram과 BAP 혼합배지가 NAA와 kinetin 혼합배지보다 더욱 효과적임을 알 수 있었다. 2. 배양제의 단백질 함량은 기관형성 과정에서 배양이 진행됨에 따라 두 처리구에서 모두 감소하였으나 picloram과 BAP 혼합처리구는 NAA와 kinetin 혼합처리구보다 낮았다. peroxidase의 활성은 이와 반대로 picloram과 BAP 혼합처리구에서 약 8배 높게 나타났다. 3. peroxidase와 malate dehydrogenase 동위효소들의 활성은 shoot가 형성됨에 따라 두 처리구 모두 증가하였으나, lactate dehydrogenase 동위효소들은 두 처리구 모두 감소하였다. 이러한 경향은 두 처리구 중에서 picloram과 BAP 혼합처리구에서 더욱 뚜렷하였다. 그러나 esterase, acid phosphatase, aspartate aminotransferase 동위효소들의 활성은 shoot 형성중에 두 처리구 모두 뚜렷한 변화가 없었다. 4. 6종류의 효소에서 분리된 동위효소의 수는 두 처리구를 합쳐 peroxidase에서 12개, acid phosphatase에서 6개, aspartate aminotransferase에서 9∼13개, lactate dehydrogenase에서 3∼5개, esterase에서 10∼16개가 각각 확인되었다. Tabaco (Nicotiana tabacum cv. NC 2326) leaf tissues were cultured on Murashige and Skoog medium containing various concentrations and combinations of some growth regulators at 26℃ for 35 days. The obtained results were summarized as follow; 1. Organ formation was 100% in shoot and 50% in root on the medium containing 0.5㎎/l NAA and 0.5㎎/l kinetin. On the medium containing 0.01㎎/l picloram and 0.5㎎/l BAP, organ formation displayed 100% multiple shoot formation and 90% root formation without callus formations. Multiple shoot formations were enhanced more by picloram and BAP groups than by NAA and kinetin groups. 2. During the shoot formation, protein content in the cultures on the medium containing picloram and BAP was lower than NAA and kinetin groups, but peroxidase activity in the former medium was higher about eight times than that in the latter medium. 3. The activity of anodic peroxidase and malate dehydrogenase isozyme increased during the shoot formation, whereas that of lactate dehydrogenase isozyme decreased. However the activity of esterase, acid phosphatase, and aspartate aminotransferase did not change. 4. All the isozymes were separated with 12 bands in peroxidase, 6 in acid phosphatase, 9∼13 in malate dehydrogenase, 3∼5 in lactate dehydrogenase, 10∼16 in esterase, 6 in aspartate aminotransferase during the shoot formation.

中高校의 英語科 敎育書를 利用한 聽取力培養方案 : 問題作成을 中心으로 Mainly on Test Making

蔡俊基 慶北大學校 語學硏究所 1981 語文硏究 Vol.6 No.-

The aim of this paper is to advocate the activities of listening comprehension in English in class and how to make test items by utilizing textbooks presently used in middle and high schools. All these activities should come from the teacher's positive attitude about the importance of using spoken English in class. Most of all, teachers should do away with scruples about non-native speakers speaking in English in class. In making tests on aural on aural comprehension, pictures, true-false, multiple-choices, dictations, directions requiring action response, questions and answers, games, and lots of other formats can be used. However, the essence of the activities is sound discrimination, understanding the meaning of a sentence, simplex or complex, understanding the meaning of a paragraph and a dialogue. All these skills require memory retention to some extent. Dictation is highly rated as an integrative test and can easily be used in class. Middle and high school textbooks are full of the materials with which teachers could make test items of aural comprehension. Examples are shown to trigger teachers' ingenuity for future test making.

유모아의 의미구조와 영어교육에의 활용

채준기 慶北大學校 語學硏究所 1988 語文硏究 Vol.13 No.-

Humor is ubiquitous in the world of human beings. Laughter means happiness and vitality in performing daily affairs and tolerance for others. The semantics of humor is deviant from the ordinary semantics of Seale's(1969) bona-fide communication mode or Grice's(1975) Coopetative Principles. The mode of semantics of humor has to be relevant to joke-telling. Presupposition and ambiguity are the backbones of humor. The funny situation of incongruity and abundant use of puns are based on the principles of presupposition and ambiguity whether the subjects of jokes are concerned with phonology, morphology, syntax or even in the matters of pragmatics. The translation of Korean and Japanese jokes into English reveals that the world of jokes has universality in its own account since most of the jokes of one language are understandable to the people of another even though the delicacy that each language put forth in jokes are beyond translation. Jokes are useful teaching materals in teaching English. Well chosen humorous stories and good jokes can give students incentive to learn English and some relaxation in classes. Besides jokes can teach students sociolinguistic sides of English language more effectively than other materials.

학교체육시설을 활용한 사회체육활성화에 대한 교사의 인식연구

홍준기 中央大學校 韓國敎育問題硏究所 2002 韓國敎育問題硏究所論文集 Vol.- No.17

The purpose of this study was to invetigate the possibilities of using the school physical training facilities for sport for all. Physical education teachers of primary and secondary schools participated in the survey dealing with the teachers' perception on the use of school physical facilities, problems, and the precondition of it. The results indicated that following actions should be taken to achieve sport for all using the school physical facility. First, school physical facilities must be supplemented quantitatively and quantitatively. Second, the cooperative system between schools and local residents should be established. Third, economic and political supports need to be backed up.

國內轉換社債發行의 資本市場反應에 관한 硏究

石琪濬,黃允植 동아대학교 경영대학 1994 經營硏究 Vol.- No.8

The purposes of this study are (1) to examine abnormal stock returns associated with announcement of convertible bond issuance, and (2) to determine firm's specific characteristics affected abnormal returns. The empirical study has selected as final sample 75 domestic convertible bond issues for the periods from 1988 to 1992. In order to examine the abnormal stock returns of announcement period and various intervals of concern, the mean adjusted model have been employed. Potential variables which determine the magnitude of abnormal returns are identified and hypothesized by reviewing prior studies. Identified variables are issuance size, difference of interest rate, market returns and probability of conversion. In order to examine the determinants of abnormal stock returns, multiple regression analyses are implemented to test statistical significance. The findings of information content can be summarized as follows : the result of domestic convertible bond shows that announcement of convertible bond issuance reduce stock prices significantly, this finding is consistent both with the hypothesis that equity issues are viewed by inversters as negative signals and with the hypothesis that there is downward sloping demand for firm's shares. The results on determinants for abnormal returns can be summarized as follows : the empirical results of regression for domestic convertible bond reveal that the coefficients of time to maturity and market return show the negative signs and are statistically significant at the 5%∼10% level and 1%∼10% level, respectively. Also, F-statistic of regression is statistically significant at the 1%∼10% level. This study provides a further evidence regarding the usefulness of convertible bond issuance to investors' decisionmaking.

事象硏究 設計上의 諸問題

石琪濬,黃允植 東亞大學校 大學院 1992 大學院論文集 Vol.17 No.-

직장항문 농양과 치루에 대한 임상적 고찰

김준호,서준하,이석환,이기형,윤충 경희대학교 1997 慶熙醫學 Vol.13 No.4

레지스터 생존시간을 줄이는 선단계 코드 스케쥴링

최준기,이상정 순천향대학교 부설 산업기술연구소 1998 순천향 산업기술연구소논문집 Vol.3 No.3

In this paper, heuristics for efficient prepass code scheduling with reducing register life times is proposed. Because code motion for scheduling makes register life time longer, the possibility of register allocation is reduced. Also, it complicates interference graph and inserts more spill codes in program. In order to resolve this program, the heuristic of this paper executes prepass code scheduling first. Then constructs dependence graph before register allocation and code motion. As a result of applying the heuristics to a program, it is verified that the complexity of the interference graph for register allocation is reduced.

英語敎育과 Aural Comprehension Test

蔡俊基 慶北大學校 師範大學 1971 敎育硏究誌 Vol.13 No.-

Structural linguists have made a great deal of contribution to the teaching of English as a foreign language. Especially C. C. Fries, the advocate of Aural-Oral Approach, made it clear that teaching and learning English must begin orally even if the ultimate aim is to read it. When part of the class activity is done orally in English, the students aural comprehension must be tested as a part of regular tests. There are several ways of making the test items: picture, true-false and multiple choice types. TOEFL and Michigan Tests give us some of the best illustrations. Kyongpuk National University has given the aural comprehension tests for the past four years as a part of English tests given to the applicants of the English Department. We hoped to arouse the students' attention as well as the teachers' at secondary schools to the importance of listening comprehension in learning a foreign language. Some of the texts, used for sound parts and item choices of the tests are included here to show ways of making the tests.